Magnetic recording and reproduction apparatus

ABSTRACT

A magnetic recording/reproduction apparatus comprises a magnetic tape running apparatus to rotate a rotary drum and run a magnetic tape with the magnetic tape being in contact with, at least, part of the circumferential surface of the rotary drum, a plurality of erasing magnetic heads installed on the rotary drum so that the magnetic tape are in contact with the heads and used to erase recording signal, a plurality of recording magnetic heads used for recording, a plurality of erasing circuits installed on the rotary drum to output erasing signal to each of the erasing magnetic heads, a plurality of recording circuits connected to the recording magnetic heads respectively and installed on the rotary drum so that the recording circuits are selectively be gone to active state and non-active state, one or more rotary transformers connected to erasing circuits in common, and a driving circuit to record information signal in the magnetic tape through recording magnetic heads, recording circuits, and rotary transformers.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. Ser. No. 07/617,081, filed onNov. 21, 1990, now abandoned, which in turn is a continuation-in-partapplication of U.S. Ser. No. 07/525,831, filed on May 18, 1990, now U.S.Pat. No. 5,276,565.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic recording and reproductionapparatus for magnetically recording and/or reproducing information byusing a magnetic tape as a recording medium.

2. Description of the Related Art

In recent years, wide-band, high-transmission rate VTRs (to be referredto as "wide-band/high-transmission rate VTRs" hereinafter) such as ahigh-resolution VTR and a digital VTR of a current TV system have beendeveloped and put into practical use. In thesewide-band/high-transmission rate VTRs, an inductance of a rotarytransformer, a stray capacitance, and a cable coupling capacitancebetween the rotary transformer and a magnetic head, which are not soproblematic in conventional VTRs, have been considered as problems. Thatis, transmission characteristics of an electromagnetic conversion systemin magnetic recording are determined by a resonance frequency obtainedby inductances of a magnetic head and a rotary transformer and the straycapacitance including an input capacitance of a reproduction circuit ina recording system, and is determined by a resonance frequency obtainedby an inductance of the magnetic head, an inductance of the rotarytransformer, and the stray capacitance including the input capacitanceof the reproduction circuit in a reproduction system. In order torealize a wide-band/high-transmission rate VTR, therefore, no rotarytransformer is desirably interposed between the magnetic head and therecording and reproduction circuits.

In a VTR of this type, therefore, as described in "Technical Bulletin ofInstitute of Electronics, Information and Communication Engineers",MR85-54, a recording circuit and a reproduction circuit are mounted in arotary drum portion and connected directly to a magnetic head withoutusing a rotary transformer, thereby widening recording and reproductionbands.

In addition, bands of a rotary transformer for transmitting signalsbetween the rotary drum portion and an external portion (between therotary drum portion and the other portion), a driver circuit for drivingthe rotary transformer, and a receiver circuit for receiving signalsfrom the rotary transformer must be simultaneously widened. That is, asthe recording and reproduction bands are determined in accordance withthe input capacitances of the magnetic head and the reproductioncircuit, a transmission band of the rotary transformer is determined inaccordance with the inductance of the rotary transformer and the inputcapacitance or the stray capacitance of the receiver circuit. Therefore,a cable having a large capacitance, e.g., a coaxial cable having a largecapacitance cannot be used to couple the driver and receiver circuits tothe rotary transformer. In order to realize a wide band of the rotarytransformer, therefore, the driver and receiver circuits must be mountedclose to the rotary transformer. As a result, a scanner (an entire drummechanism portion including a "rotary drum" and a "stationary drum" willbe referred to as a "scanner" hereinafter) is complicated and enlargedsince the driver and receiver circuits of the rotary transformer aremounted.

In addition, as described in "National Convention Record of theInstitute of Television Engineers of Japan", Vol. 10, No. 41; VR87-5; T.Eguchi et al.; January 1987, a VTR of this type must have at least sixn=magnetic heads including those for normal reproduction andspecial-purpose reproduction. For example, a D-1 format 525 digital VTRemploys 16 magnetic heads.

A rotary transformer is normally used for signal transmission between arotary drum portion and an external portion (between the rotary drumportion and the other portion), and the number of channels of the rotarytransformer must correspond to the number of magnetic heads mounted inthe rotary drum. If, however, rotary transformers are mounted in ascanner in a number corresponding to the number of multi-channelmagnetic heads, a mechanism of the scanner is enlarged and complicated,resulting in insufficient mechanical precision of each portion. Althougha recording or reproduction circuit must be provided in a numbercorresponding to the number of magnetic heads similar to the rotarytransformer, it can be made compact and light by adopting an ICarrangement. Since, however, the rotary transformer must have a widerange and a low crosstalk between channels, its miniaturization islimited.

In order to simplify an arrangement of the mechanism of the scanner andthat of an electronic circuit including the recording and thereproduction circuits. therefore, the number of channels of the rotarytransformer must be reduced.

In addition, since the recording and reproduction circuits correspondingto the multi-channel magnetic head are mounted, power consumption isincreased. Furthermore, since thermal expansion is caused in eachmechanism portion of the scanner due to heat generated by circuitelements, precision of the mechanism is degraded. Therefore, low powerconsumption is also required for the recording and reproduction circuitsto be mounted in the rotary drum and a circuit portion at the stationarydrum side.

SUMMARY OF THE INVENTION

It is, an object of the present invention to provide a magneticrecording and reproduction apparatus which can reduce the number ofchannels of a rotary transformer without degrading frequencycharacteristics, reduce power consumption of the entire circuit mountedon a rotary drum, and simplify and miniaturize a mechanism of a scannerportion.

According to the invention, these is provided a magneticrecording/reproduction apparatus comprising: a rotary drum having acircumferential surface; tape running means for rotating said rotarydrum and run a magnetic tape by making the magnetic tape as a recordingmedium contact with, at least, part of the circumferential surface ofsaid rotary drum; a plurality of magnetic heads installed on said rotarydrum so that said magnetic tape will contact them; a plurality ofamplifying circuit means respectively connected to said magnetic headsand installed on said rotary drum said amplifying means beingselectively gone to active state and non-active state; at least onerotary transformer having a core in which a slot is formed, at least oneconductor to be received to said slot, and lead wires integrally formedwith said conductor, and being connected to said amplifying circuitmeans in common; and control means for making said magnetic headsexecute at least one of data-recording and data-reproduction throughsaid amplifying circuit means, and said rotary transformer.

According to the invention, there is provided a magneticrecording/reproduction apparatus comprising a rotary drum havingcircumferential surface; tape running means for rotating the rotary drumand run a magnetic tape with the magnetic tape as a recording mediumbeing in contact with, at least, part of the circumferential surface ofthe rotary drum; magnetic head means having a plurality of firstmagnetic heads used for erasing a record signal and installed on therotary drum so that the magnetic tape is in contact with the firstmagnetic heads and a plurality of second magnetic heads used forperforming at least one of recording and reproduction; a plurality oferasing circuit means installed on the rotary drum to output erasingsignal to each of the first magnetic heads; a plurality of amplifyingcircuit means connected to the second magnetic heads respectively andinstalled on the rotary drum, the amplifying means being selectivelygone to active state and nonactive state; at least one rotarytransformer connected to the erasing circuit means in common; andcontrol means for making the second magnetic heads execute at least oneof recording and reproduction through the amplifying circuit means andthe rotary transformer.

According to the invention, there is provided a magneticrecording/reproduction apparatus comprising, a rotary drum having acircumferential surface; tape running means for rotating the rotary drumand running a magnetic tape with the tape as a recording medium being incontact with, at least, part of the circumferential surface of therotary drum; magnetic head means having a plurality of erasing magneticheads installed on the rotary drum so that the magnetic tape is incontact with the heads, and used for erasing record signal and aplurality of recording magnetic heads used for recording informationsignal in the magnetic tape; a plurality of erasing circuit meansinstalled on the rotary drum to output erasing signal to each of theerasing heads; a plurality of recording circuit means connected to therecording magnetic heads respectively and installed on the rotary drumso that the recording circuit means are selectively gone to active stateand non-active state; at least one of rotary transformer connected to atleast one of the recording circuit means and the erasing circuit meansin common; and driving means for recording information signal in themagnetic tape through the recording magnetic heads, the recordingcircuit means, and the rotary transformers.

According to the invention, there is provided a magneticrecording/reproduction apparatus comprising, a rotary drum having acircumferential surface; tape running means for rotating the rotary drumand running a magnetic tape with the magnetic tape being in contactwith, at least, part of the circumferential surface of said rotary drum;magnetic head means having a plurality of erasing magnetic headsinstalled on said rotary drum so that said magnetic tape is in contactwith the heads and used for erasing recording signal and a plurality ofreproduction magnetic heads used for reproducing the recording signalfrom said magnetic tape; a plurality of erasing circuit means installedon said rotary drum to output erasing signal to each of said erasingheads; a plurality of reproduction circuit means connected to saidreproduction magnetic heads respectively and installed on said rotarydrum so that the reproduction circuit means are selectively gone toactive state and non-active state; at least one rotary transformerconnected to at least one of said reproduction circuit means and saiderasing circuit means; and means for reproducing record signal from saidmagnetic tape through said reproduction magnetic heads, saidreproduction circuit means, and said rotary transformer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention and, together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a schematic view showing a basic arrange ment of a scannerportion of a magnetic recording and reproduction apparatus according tothe first embodiment of the present invention;

FIG. 2 is a circuit diagram showing a practical circuit having the basicarrangement shown in FIG. 1;

FIG. 3 is a timing chart showing a series of time sequences of aswitching operation for recording and reproduction circuits in theapparatus shown in FIGS. 1 and 2;

FIG. 4 is a circuit diagram showing a basic arrangement of a circuit forincreasing an impedance of an output from the reproduction circuit;

FIGS. 5A and 5B are block diagrams showing basic circuit arrangements ofrecording and reproduction systems, respectively, of the magneticrecording and reproduction apparatus according to the first embodimentof the present invention;

FIG. 6 is a schematic view showing a basic arrangement of a scannerportion of a magnetic recording and reproduction apparatus according tothe second embodiment of the present invention;

FIG. 7 is a circuit diagram showing a practical circuit having thearrangement shown in FIG. 6;

FIG. 8 is a timing chart showing a series of time sequences of aswitching operation for recording and reproduction circuits of theapparatus shown in FIGS. 6 and 9;

FIG. 9A and 9B show a basic arrangement according to a first arrangementof a selective switching device, used in the first embodiment of thepresent invention shown in FIGS. 1 and 2, for generating a timing signalfor performing switching upon each 180° rotation, in which FIG. 9A is aschematic sectional view of a cylinder system and FIG. 9B is a schematicplan view thereof:

FIG. 10 is a block diagram showing an arrangement of a circuit forperforming selective control in the embodiment shown in FIGS. 9A and 9B;

FIG. 11 is a timing chart showing a series of sequences of a switchingoperation in the embodiment shown in FIGS. 9A and 9B;

FIGS. 12A and 12B show a basic arrangement according to a secondarrangement of the selective switching device for generating a timingsignal for performing switching upon each 180° rotation, in which FIG.12A is a schematic sectional view of a cylinder system and FIG. 12B is aschematic plan view thereof;

FIG. 13 is a schematic view showing an arrangement of a reflection typephoto sensor for explaining a principle of the present invention;

FIGS. 14A and 14B show a basic arrangement according to a thirdarrangement of the selective switching device for generating a timingsignal upon each 180° rotation;

FIG. 15 is a schematic view for explaining an arrangement of a rotarytransformer portion of one channel and its peripheral circuit associatedwith the recording system according to the first embodiment of thepresent invention;

FIG. 16 is a schematic view for explaining an arrangement of a rotarytransformer portion of one channel and its peripheral circuit associatedwith the reproduction system according to the first embodiment of thepresent invention;

FIG. 17 is a schematic view for explaining an arrangement of a rotarytransformer portion of one channel and its peripheral circuit associatedwith the recording and reproduction systems according to the secondembodiment of the present invention;

FIG. 18 is a schematic plan view for explaining an arrangement of arotary member or a stationary member of a rotary transformer unit foruse in the third, fourth, and fifth embodiments of the presentinvention;

FIG. 19 is a schematic view for explaining an arrangement of a main partof the third embodiment of the present invention using, for recording, arotary transformer unit having a rotary member as shown in FIG. 18 and astationary member in which a winding is wound in a winding slot;

FIG. 20 is a timing chart showing a series of sequences of an operationassociated with switching of a recording circuit according to theembodiment shown in FIG. 19;

FIG. 21 is a schematic view for explaining an arrangement of a main partof the fourth embodiment of the present invention using, for recording,a rotary transformer unit having a rotary member as shown in FIG. 18 anda stationary member in which a winding is wound in a winding slot;

FIG. 22 is a timing chart showing a series of sequences of an operationassociated with switching of a reproduction circuit according to theembodiment shown in FIG. 21;

FIG. 23 is a schematic view for explaining an arrangement of a main partof the fifth embodiment of the present invention using, for recordingand reproduction, a rotary transformer unit having a rotary member asshown in FIG. 18 and a stationary member in which a winding is wound ina winding slot;

FIG. 24 is a timing chart showing a series of sequences of an operationassociated with switching of the recording and reproduction circuits ofthe embodiment shown in FIG. 23;

FIGS. 25 and 26 are sectional views for explaining problems of a rotarytransformer apparatus for performing signal transmission between arotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 27 is a sectional view schematically showing an arrangement of thesixth embodiment of the present invention for solving problems of arotary transformer apparatus for performing signal transmission betweena rotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 28 is a sectional view schematically showing an arrangement of theseventh embodiment of the present invention for solving problems of arotary transformer apparatus for performing signal transmission betweena rotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 29 is a sectional view schematically showing an arrangement of theeight embodiment of the present invention for solving problems of arotary transformer apparatus for performing signal transmission betweena rotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 30 is a sectional view schematically showing an arrangement of theninth embodiment of the present invention for solving problems of arotary transformer apparatus for performing signal transmission betweena rotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 31 is a sectional view schematically showing an arrangement of thetenth embodiment of the present invention for solving problems of arotary transformer apparatus for performing signal transmission betweena rotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 32 is a sectional view schematically showing an arrangement of the11th embodiment of the present invention for solving problems of arotary transformer apparatus for performing signal transmission betweena rotary member and a stationary member in which a plurality of windingsare wound in a single slot of one member while a single winding is woundin a slot of the other member;

FIG. 33 is a plan view schematically showing an arrangement of onemember shown in FIG. 31;

FIG. 34 is a sectional view schematically showing an arrangement of the12th embodiment of the present invention;

FIG. 35 is a sectional view schematically showing an arrangement of the13th embodiment of the present invention;

FIG. 36 is a sectional view schematically showing an arrangement of the14th embodiment of the present invention;

FIG. 37 is a sectional view schematically showing an arrangement of the15th embodiment of the present invention;

FIG. 38 is a sectional view schematically showing an arrangement of the16th embodiment of the present invention;

FIG. 39 is a sectional view schematically showing an arrangement of the17th embodiment of the present invention;

FIG. 40 is a sectional view schematically showing an arrangement of the18th embodiment of the present invention;

FIG. 41 is a sectional view schematically showing an arrangement of the19th embodiment of the present invention;

FIG. 42 is a sectional view schematically showing an arrangement of the20th embodiment of the present invention;

FIG. 43 is a sectional view schematically showing an arrangement of the21st embodiment of the present invention;

FIG. 44 is a sectional view schematically showing an arrangement of the22nd embodiment of the present invention and;

FIG. 45 is a sectional view schematically showing an arrangement of the23rd embodiment of the present invention;

FIG. 46 is a top view of a rotary transformer winding;

FIG. 47 is a perspective view of the rotary transformer winding;

FIG. 48 is a sectional view of the rotary transformer;

FIG. 49 is a top view of a rotary transformer winding covered withinsulation sheath;

FIG. 50 is a sectional view of the rotary transformer;

FIG. 51 is a top view of the winding according to a modified embodimentof the rotary transformer;

FIG. 52 is a top view of the winding according to another modifiedembodiment of the rotary transformer;

FIG. 53 is a sectional view of a rotary transformer with a doublewinding;

FIG. 54 is a schematic block diagram of a rotary drum provided with anerasing head;

FIG. 55 is a circuit diagram of a circuit for switching erasingcircuits;

FIG. 56 is a timing chart for describing the operation of the erasingcircuits in FIG. 55;

FIG. 57 is a schematic block diagram of a rotary drum provided witherasing heads according to another embodiment;

FIG. 58 is a circuit diagram of a circuit for switching the erasingcircuits installed on the rotary drum in FIG. 57;

FIG. 59 is a timing chart for describing the operation of the erasingcircuits in FIG. 58;

FIGS. 60A and 60B show a detection system for switching erasingcircuits;

FIG. 61 shows a flip-flop circuit to control switching of erasingcircuits;

FIG. 62 is a timing chart for describing the switching operation oferasing circuits;

FIGS. 63A and 63B show a detection system for switching the erasingcircuits according to another modified embodiment;

FIG. 64 shows a photodetector used for switching erasing circuits;

FIGS. 65A and 65B show a detection system for switching the erasingcircuits according to the third modified embodiment;

FIG. 66 is a schematic block diagram of the rotary drum of a magneticrecording/reproduction apparatus provided with the erasing headsaccording to another embodiment with the tap lap angle of 90°;

FIG. 67 is a circuit diagram of a circuit for switching the erasing andrecording circuits installed on the rotary drum in FIG. 66;

FIG. 68 is a timing chart for describing the operation of the erasingcircuits in FIG. 67;

FIG. 69 is a schematic block diagram of the rotary drum of a magneticrecording/reproduction apparatus provided with the erasing headsaccording to another embodiment with the tape lap angle of 120°;

FIG. 70 is a circuit diagram of a circuit for switching the erasing andrecording circuits installed on the rotary drum in FIG. 69;

FIG. 71 is a timing chart for describing the operation of the circuit inFIG. 70;

FIGS. 72A and 72B show a detection system for switching the erasing andrecording circuits according to another modified embodiment;

FIGS. 73A and 73B show a detection system for switching the erasing andrecording circuits according to the third modified embodiment;

FIG. 74 is a schematic block diagram of the rotary drum of a magneticrecording/reproduction apparatus provided with the erasing headsaccording to another embodiment;

FIG. 75 is a circuit diagram of a circuit for switching the erasing,recording, and reproduction circuits installed on the rotary drum inFIG. 74;

FIG. 76 is a timing chart for describing the operation of the circuitsin FIG. 75;

FIG. 77 is a circuit diagram of a multiple-channel recording apparatususing a rotary transformer;

FIGS. 78A through 83B show the rotary drums with variously-arrangedrecording magnetic heads and the recording signals corresponding tothem;

FIG. 84 is a circuit diagram of a recording apparatus using a rotarytransformer with several winding in one slot;

FIG. 85 is a circuit diagram of a multiple-channel reproductionapparatus using one rotary transformer;

FIGS. 86A through 91B show the rotary drums with variously-arrangedreproduction magnetic heads and reproduction signals corresponding tothem;

FIG. 92 is a circuit diagram of a reproduction apparatus using a rotarytransformer with several windings in one slot;

FIG. 93 is a circuit diagram of a multiple-channelrecording/reproduction apparatus using one rotary transformer forrecording and reproduction respectively;

FIGS. 94A through 95B show the rotary drums with variously-arrangedreproduction magnetic heads and the reproduction signals correspondingto them;

FIG. 96A is a circuit diagram of a magnetic recording/reproductionapparatus using a rotary transformer with several windings in one slotfor recording and reproduction respectively;

FIG. 96B shows the arrangement of magnetic heads on the apparatus inFIG. 96A;

FIGS. 97 through 106 show circuit diagrams of various magneticrecording/reproduction apparatuses using magnetic heads dedicated torecording and those dedicated to reproduction; and

FIGS. 107 through 118 show circuit diagrams of various magneticrecording/reproduction apparatuses using magnetic heads for bothrecording and reproduction.

FIG. 119 is a circuit diagram of the scanner section of a magneticrecording/reproduction apparatus using a rotary transformer with aplurality of windings in a single winding slot;

FIGS. 120A and 120B are block diagrams of a recording system and areproduction system of a magnetic recording/reproduction apparatus usinga rotary transformer with a plurality windings in a single winding slot;

FIG. 121 is a circuit diagram of the scanner section of a magneticrecording/reproduction apparatus using a rotary transformer with aplurality windings in a single winding slot;

FIG. 122 is a circuit diagram of a magnetic recording/reproductionapparatus using a rotary transformer with a plurality windings in asingle winding slot and an erase head;

FIG. 123 is a circuit diagram of a magnetic recording/reproductionapparatus using a rotary transformer with a plurality windings in asingle winding slot and an erase head;

FIG. 124 is a circuit diagram of a magnetic recording/reproductionapparatus using a rotary transformer with a plurality windings in asingle winding slot, a recording head, and an erase head;

FIG. 125 is a circuit diagram of a magnetic recording/reproductionapparatus using a rotary transformer with a plurality windings in asingle winding slot, a recording head, and an erase head;

FIG. 126 is a circuit diagram of a magnetic recording/reproductionapparatus using a rotary transformer with a plurality windings in asingle winding slot, an erase head, a reproduction head, and a recordinghead;

FIG. 127 is a schematic sectional view of a scanner including a rotarytransformer in which a plurality of windings are provided;

FIG. 128 is a sectional view of a scanner taken along line A--A of FIG.127;

FIG. 129 is a sectional view of a coaxial rotary transformer;

FIG. 130 is a sectional view of a double coaxial rotary transformer;

FIG. 131 is a sectional view of another double coaxial rotarytransformer;

FIG. 132 is a sectional view of a coaxial rotary transformer;

FIG. 133 is a schematic view of a position sense unit for switchingmagnetic heads;

FIG. 134 is a view showing a mounting arrangement of an LED array;

FIG. 135 is a view showing a mounting arrangement of an LED array;

FIG. 136 is a view showing a mounting arrangement of an LED array;

FIG. 137 is a view showing a mounting arrangement of an LED array;

FIG. 138 is a view showing a mounting arrangement of an LED array;

FIG. 140 is a view showing a mounting arrangement of an LED array;

FIGS. 141A and 14lB are connection diagrams of an LED array;

FIGS. 142A and 142B are connection diagrams of an LED array;

FIG. 143 is a view showing the internal construction of a package towhich the MCP system is applied;

FIG. 144 is a block diagram showing the construction of a recordingcircuit with a carrier sensing function according to the presentinvention;

FIG. 145 is a block diagram showing a construction of the full-waverectifying RF detector of FIG. 144;

FIG. 146 is an illustration of operating waveform charts for variousparts of FIG. 145;

FIG. 147 is a block diagram showing another construction of thefull-wave rectifying RF detector of FIG. 144;

FIG. 148 is operating waveform charts for various parts of FIG. 147;

FIG. 149 is a block diagram showing another construction of thefull-wave rectifying RF detector of FIG. 144;

FIG. 150 is an illustration of operating waveforms for various parts ofFIG. 149;

FIG. 151 is a block diagram showing another construction of thefull-wave rectifying RF detector of FIG. 144;

FIG. 152 is an illustration of operating waveforms for various parts ofFIG. 151 with respect to a sine-wave RF signal;

FIG. 153 is an illustration of operating waveforms for various parts ofFIG. 151 with respect to a square-wave RF signal;

FIG. 154 is a block diagram showing another construction of thefull-wave rectifying RF detector of FIG. 144;

FIG. 155 is an illustration of operating waveforms for various parts ofFIG. 154;

FIG. 156 is a block diagram showing the construction of a recordingcircuit with a 180° switching control function according to the presentinvention;

FIG. 157 is a time chart for the operation of the FIG. 156 recordingcircuit during normal recording;

FIG. 158 is a time chart for the operation of the FIG. 156 recordingcircuit during insert recording;

FIG. 159 is a block diagram showing the construction of a recordingcircuit with a 180° switching control function according to the presentinvention;

FIG. 160 is a time chart for the operation of the FIG. 159 recordingcircuit during normal recording;

FIG. 161 is a time chart for the operation of the FIG. 159 recordingcircuit during insert recording;

FIG. 162 is a block diagram showing the construction of a recordingcircuit with a 180° switching control function according to the presentinvention;

FIG. 163 is a time chart for the operation of the FIG. 162 recordingcircuit during normal recording;

FIG. 164 is a time chart for the operation of the FIG. 162 recordingcircuit during insert recording;

FIG. 165 is a block diagram showing a construction of the FIG. 162 issignal amplitude sense circuit;

FIG. 166 is a time chart for the operation of the signal amplitude sensecircuit of FIG. 165;

FIG. 167 is a sectional view for explaining a manufacturing method ofcoaxial rotary transformer apparatuses according to the presentinvention;

FIG. 168 is a sectional view of a coaxial rotary transformer apparatus;

FIG. 169A through 169C are perspective view for explaining themanufacturing processes of coaxial rotary transformer apparatusesaccording to the present invention;

FIG. 170A through 170D are views for explaining the construction of thereproduction circuit board unit in the scanner section of the presentinvention and its manufacturing processes;

FIG. 171 is a view of another example of the reproduction circuit boardunit;

FIG. 172 is a sectional view showing a mounting arrangement of arecording circuit board unit, a reproduction circuit board unit, arecording LED array, a recording photodetector, a reproduction LEDarray, and a reproduction photodetector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings.

FIG. 1 schematically shows a basic arrangement of a scanner portion of amagnetic recording and reproduction apparatus according to the firstembodiment of the present invention. FIG. 2 shown a practical circuithaving the arrangement shown in FIG. 1 and FIG. 3 shows a series of timesequences of a switching operation of the recording and reproductioncircuits.

In the first embodiment, assume that an effective recording area angleof a magnetic tape 2 is 180°. The magnetic tape 2 is wound around thecircumferential surface of a rotary drum of a scanner 1. The tape 2 isin contact with the circumferential surface of the rotary drum through180°. This contact portion serves as an effective recording area of aninformation signal of the tape 2.

A recording circuit 3a amplifies an information signal supplied from arotary transformer 6a (shown in FIG. 2) and supplies the amplifiedsignal to a recording magnetic head R1, thereby driving the magnetichead R1. A recording magnetic head R2 is arranged at a position shiftedfrom the magnetic head R1 by 180° so that the rear surfaces of the twoheads oppose each other. The magnetic head R2 is driven by a recordingcircuit 3b having an input side commonly connected to the recordingcircuit 3a. The information signal is reproduced from the magnetic tape2 to a reproduction magnetic head P1, amplified by a reproductioncircuit 4a, and transmitted outside the rotary drum by a a rotarytransformer 6b (shown in FIG. 2) connected to the output side of thereproduction circuit 4a. A reproduction magnetic head P2 is arranged ata position shifted from the magnetic head P1 by 180° so that the rearsurfaces of the two heads oppose each other. An information signalreproduced by the magnetic head P2 is amplified by a reproductioncircuit 4b having an output side commonly connected to the reproductioncircuit 4a.

An information signal (to be referred to as an "RF signal" hereinafter)to be recorded in a magnetic tape is amplified by a rotary transformerdriving circuit 5 as an amplifier and transmitted to the rotary drumportion by the rotary transformer 6a. The RF signal to be input to therotary transformer driving circuit 5 includes both information signalsto be recorded by the magnetic heads R1 and R2. The recording circuits3a and 3b have input sides commonly connected to the rotary transformer6a. As shown in FIG. 3, the recording circuits 3a and 3b are alternatelyswitched to enable and disable states upon each 180° rotation by R1 andR2 selection signals having opposite phases, respectively. The recordingcircuit 3a (3b) amplifies the input RF signal in its enable state anddrives the magnetic head R1 (R2) by the amplified RF signal, therebyrecording the RF signal corresponding to an R1 (R2) recording current ina magnetic tape.

Reproduction of the RF signal recorded in the magnetic tape will bedescribed below. The RF signals reproduced from the magnetic tape by themagnetic heads P1 and P2 are amplified by the reproduction circuits 4aand 4b, respectively. The rotary transformer 6b commonly connected tothe output sides of both the reproduction circuits 4a and 4b is drivento transmit the reproduced RF signals outside the rotary drum portion.As shown in FIG. 3, the reproduction circuits 4a and 4b are alternatelyswitched to enable and disable states upon each 180° rotation by P1 andP2 selection signals having opposite phases, respectively. P1 and P2reproduced signals as reproduced RF signals reproduced from the magneticheads P1 and P2 in the enable state are transmitted outside the rotarydrum portion by the commonly connected rotary transformer 6b. The P1 andP2 reproduced signals transmitted from the rotary transformer 6b arereceived by a rotary transformer receiving circuit 7, amplified asneeded, and transmitted to the following circuit as an RF signal output.The RF signal output supplied from the rotary transformer receivingcircuit 7 upon this switching operation includes both the RF signalsreproduced from the magnetic heads P1 and P2, i.e., both the P1 and P2reproduced signals.

A method of reducing the number of channels of the rotary transformers6a and 6b will be described below.

The input sides of the recording circuits 3a and 3b are commonlyconnected to the rotary transformer. Therefore, in order to preventdegradation in frequency characteristics of the recording circuits 3aand 3b, emitter followers or Darlington emitter followers are used ascircuits of input stages of the circuits 3a and 3b so as to increasetheir input impedances. The outputs of the reproduction circuits 4a and4b are commonly connected to the rotary transformer. Therefore, in orderto prevent degradation in frequency characteristics of one of thereproduction circuits 4a and 4b in an enable state, an output of theother reproduction circuit in a disable state is kept in ahigh-impedance state.

For example, the circuit shown in FIG. 4 is used to cause the outputimpedance of the reproduction circuit to be high. Although the outputsof the reproduction circuits according to this embodiment are balancedoutputs, only one side output is shown to simplify the explanation. In areproduction circuit of this type, an emitter follower or a Darlingtonemitter follower is normally used as an output stage in order to obtainsufficient driving power against a load. Referring to FIG. 4, atransistor Q1 having an emitter follower connection is used. Atransistor Q2, a diode D1, and resistors Z1 and Z2 constitute a constantcurrent circuit for flowing a constant current to the emitter followertransistor Q1. Switching between enable and disable states of theemitter follower is performed by transistors Q3 and Q4 and an inverterIN1. When a selection signal is at "H" (high level), the bases of thetransistors Q3 and Q4 go to "L" (low level). Therefore, the transistorsQ3 and Q4 are turned off, and the emitter follower of the transistor Q1operates to output an RF signal. When the selections signal is at "L",the bases of the transistors Q3 and Q4 go to "H" . Therefore, thetransistors Q3 and Q4 are turned on, and the base of the emitterfollower transistor Q1 goes to "L". Therefore, the transistor Q1 isturned off to set its output in a high-impedance state.

A method of simplifying a circuit by adopting the arrangement of thisembodiment will be described below.

FIGS. 5A and 5B show circuits of recording and reproduction systemsadopting this embodiment, respectively.

Each arrangement has 16 heads by a so-called 180° lap in which two headsof each pair are arranged through 180° so that their rear surfacesoppose each other. An input video signal is converted into a digitalsignal by an A/D (analog-to-digital) converter 101, and the converteddigital signal is distributed to and encoded by eight encoders 102. Eachof the eight divided signals is input to a stator side of acorresponding one of eight rotary transformers 105 via a correspondingpair of eight modulators 103 and eight rotary transformer drivers 104.16 recording heads 107 provided at rotor sides of the rotarytransformers 105 are connected to recording amplifiers 106 and to therotor sides of the eight rotary transformers 105 by the arrangement asdescribed above.

In a circuit of the reproduction system according to this embodimentshown in FIG. 6B, only eight rotary transformers 120 are required for 16reproduction heads 122, and the number of each of rotary transformerreceivers 119, equalizers 118, AGC (automatic gain controllers) circuits117, and comparators 116 for analog-to-digital conversion is only eight.In FIG. 6B D/A (digital-to-analog) converter 108, decoder 109, time-basecorrectors 110, demodulators 111, frame synchronization circuits 112,data discriminators 113, clock reproduction circuits 114, referenceclock generator 115 and reproduction amplifiers 121 are also shown.

FIG. 6 shows a schematic basic arrangement of a scanner portion of amagnetic recording and reproduction apparatus according to the secondembodiment of the present invention. FIG. 7 shows a practical circuithaving the arrangement shown in FIG. 6. Similar to the above firstembodiment, a magnetic tape 2 is wound around the circumferentialsurface of a rotary drum of a scanner 1. The tape 2 is in tight contactwith the circumferential surface of the rotary drum through 180°, andthis contact portion serves as an effective recording area of aninformation signal of the tape 2. In this embodiment, recording andreproduction circuits are commonly connected to a rotary transformer. Arecording circuit 3a amplifies an information signal supplied from arotary transformer 6a and supplies the amplified signal to a magnetichead R1, thereby driving the recording magnetic head R1 by theinformation signal. A reproduction magnetic head P1 is arranged at aposition on the rotary drum shifted from the magnetic head by 180°. Aninformation signal reproduced from the magnetic tape by the magnetichead P1 is amplified by a reproduction circuit 4 a and transmittedoutside the rotary drum via the rotary transformer 6a connected to theoutput of the reproduction circuit 4a. A recording magnetic head R2 isdriven by a recording circuit 3b. A reproduction magnetic head P2 isarranged at a position shifted from the magnetic head R2 by 180°. Aninformation signal is amplified by a reproduction circuit 4b having anoutput side commonly connected to the input side of a recording circuit3b. A rotary transformer 6b is used to transmit an RF signal to therecording circuit 3b and to transmit an RF signal outside the rotarydrum portion from the reproduction circuit 4b.

An information signal to be recorded in a magnetic tape, i.e., an RFsignal is amplified by a rotary transformer driving circuit 5a andtransmitted into a rotary drum by a rotary transformer 6a. A recordingcircuit 3a having an input side connected to the rotary transformer 6ais sequentially switched between enable and disable states upon each180° rotation by an R1 selection signal (to be described later). Whenthe recording circuit 3a is in the enable state, a magnetic head R1 isdriven to record the RF signal in the magnetic tape.

Reproduction of the RF signal from the magnetic tape will be describedbelow. The RF signal reproduced from the magnetic tape by a magnetichead P1 is amplified by a reproduction circuit 4a and supplied to therotary transformer 6a to which the output side of the reproductioncircuit 4a and the input side of the recording circuit 3a are commonlyconnected. The rotary transformer 6a transmits the reproduced RF signalsupplied from the reproduction circuit 4a to outside the rotary drum.The reproduction circuit 4a is sequentially switched between enable anddisable states upon each 180° rotation by a P1 selection signal P1. Whenthe reproduction circuit 4a is in the enable state, the RF signalreproduced from the magnetic head P1 is transmitted outside the rotarydrum by a rotary transformer 6b. The reproduced RF signal transmittedfrom the rotary transformer 6b is received by a rotary transformerreceiving circuit 7b and transmitted to a circuit at a subsequent stage.Note that an operation of a system of a rotary transformer drivingcircuit 5b, the rotary transformer 6b, a recording circuit 3b, areproduction circuit 4b, and the rotary transformer receiving circuit 7bis similar to that of the above circuit.

An arrangement of an output circuit of the reproduction circuit 4 andthe rotary transformer receiving circuit 7 may be the same as that ofthe circuit shown in FIG. 4. Note that a circuit associated withswitching selection of the rotary transformer receiving circuit 7 is notshown.

FIG. 8 shows a series of time sequences of a switching operation of theabove recording and reproduction circuits.

A method of sequentially switching the recording or reproduction circuitupon each 180° rotation and a device therefor (to be referred to as a"selective switching device" hereinafter) will be described below.

FIGS. 9A and 9B show a basic arrangement of a first arrangement of aselective switching device according to the first embodiment of thepresent invention described above. FIG. 9A is a schematic sectional viewshowing a scanner (cylinder system), and FIG. 9B is a schematic planview of the system.

A rotary drum 8 has photodetectors 13a, 13b, 14a, and 14b, and astationary drum 9 has a recording LED (light-emitting diode) 11 and areproduction LED 12. A recording circuit is controlled by the recordingLED 11 at the stationary drum 9 side, a reproduction circuit iscontrolled by the reproduction LED 12, and the recording andreproduction LEDs 11 and 12 are controlled by a recording/reproductioncontroller 10. The photodetectors at the rotary drum 8 side for directlycontrolling the recording and reproduction circuits in response tocontrol light from the recording and reproduction LEDs 11 and 12 aremounted in a rotation position corresponding to a rotation position of arecording and reproduction heads. That is, as shown in FIG. 9B, thephotodetector 13a for controlling the recording circuit of a magnetichead R1 is provided at the same rotation position as that of themagnetic head R1, and the photodetector 13b for controlling therecording circuit of a magnetic head R2 is provided at the same rotationposition as that of the magnetic head R2. The photodetector 14a forcontrolling the reproduction circuit of a magnetic head P1 is providedat the same rotation position as that of the magnetic head P1, and thephotodetector 14b for controlling the recording circuit of a magnetichead P2 is provided at the same rotation position as that of themagnetic head P2.

An operation of the selective switching device will be described belowwith reference to FIGS. 9A, 9B, and 10. FIG. 11 shows a series of timesequences of the switching operation of the selective switching device.

In order to simplify the explanation, assume that both the recording andreproduction LEDs 11 and 12 are turned on (to emit light) by therecording/reproduction controller 10.

A recording system will be described first. Referring to FIG. 9B, sincethe rotary drum 8 rotates in a direction indicated by an arrow and thepositions of the photodetector 13a and the recording LED 11 coincidewith each other, the photodetector 13a outputs an "H" signal. Therefore,since the output of the photodetector 13a is connected to the set inputterminal of a set/reset flip-flop 15a, the "H" signal is output from theQ output terminal of the flip-flop 15a. when the rotary drum 8 furtherrotates in the direction indicated by the arrow shown in FIG. 9B, theoutput from the photodetector 13a goes to "L". when the rotary drum 8rotates through 180°, an output from the photodetector 13b connected tothe reset input terminal of the flip-flop 15a goes to "H". Therefore, aQ output from the flip-flop 15a goes to "L". Thereafter, Q and Q outputsfrom the flip-flop 15a sequentially, repeatedly go to "H" and "L" uponeach 180° rotation of the rotary drum 8. The Q output of "H" level fromthe flip-flop 15a controls the R1 recording circuit to be in an enablestate, while the Q outputs of "L" level controls the R1 recordingcircuit to be in a disable state. The Q output of "H" level from theflip-flop 15a controls the R2 recording circuit to be in an enablestate, while the Q output of "L" level controls the R2 recording circuitto be in a disable state.

An operation of a circuit of the reproduction system is basically thesame as that of the recording circuit. Note that the photodetector 14astarts its operation 90° after the photodetector 13a and thephotodetector 14b starts its operation 90° after the photodetector 13b.Q and Q outputs from a set-reset flip-flop 15b sequentially go to "H"and "L" upon each 180° rotation of the rotary drum 8. When the Q outputfrom the flip-flop 15b is at "H" level, the P1 reproduction circuit isset in an enable state. When the Q output is at "L" level, the P1reproduction circuit is set in a disable state. When the Q output fromthe flip-flop 15b is at "H" level, the P2 reproduction circuit is set inan enable state. When the Q output is at "L" level, the P2 reproductioncircuit is set in a disable state.

Note that the recording and reproduction LEDs 11 and 12 areON/OFF-controlled in accordance with a mode of a VTR. That is, only therecording LED 11 is turned on in a recording mode, only the reproductionLED 12 is turned on in a reproduction mode, and both the recording andreproduction LEDs 11 and 12 are turned on in a simultaneousreproduction/recording mode.

FIGS. 12A and 12B show a basic arrangement of a second arrangement ofthe selective switching device. FIG. 12A is a schematic sectional viewshowing a scanner system, and FIG. 12B is a schematic plan view of thesystem. In this arrangement, as shown in FIG. 12B, reflection type photosensors 16a, 16b, 17a, and 17b for controlling recording andreproduction are mounted at a rotary drum 8 side at positionscorresponding to magnetic heads R1, R2, P1, and P2, respectively. If anangle of an effective recording area is 180°, a reflective portion,e.g., a mirror is arranged at a recording side of a stationary drum 9,and a non-reflective portion which cannot be detected by a reflectiontype photo sensor is arranged at its nonrecording side. Note that eachof the reflection type photo sensors 16a, 16b, 17a, and 17b is a unitconstituted by an LED 18 and a photodetector 19 such as a photodiode orphototransistor as shown in FIG. 13. Various types of reflection typephoto sensors are available. For example, an "H" signal is output when areflective portion is present on an opposing surface, and an "L" signalis output when no reflective portion is present.

In this embodiment, an arrangement using a photo sensor which outputsthe signals as described above is used. The rotary drum rotates in adirection indicated by an arrow shown in FIG. 12B, and the recordingcircuit of the magnetic head R1 is controlled by the reflection typephoto sensor 16a and set in an enable state when it passes through arecording area side having a reflective portion. The recording circuitis set in a disable state when it passes through a non-reflectiveportion. Similarly, the recording circuit of the magnetic head R2 iscontrolled by the reflection type photo sensor 16b, the reproductioncircuit of the magnetic head P1 is controlled by the reflection typephoto sensor 17a, and the reproduction circuit of the magnetic head P2is controlled by the reflection type photo sensor 17b. In thisembodiment, the reflection type photo sensors 16a, 16b, 17a, and 17bgenerate a 180° selection signal which can be input directly to therecording or reproduction circuit. In this case, switching betweenrecording and reproduction is performed by a signal supplied to thephoto sensors 16a, 16b, 17a, and 17b via, e.g., a slip ring.

According to the arrangement of this embodiment, in the arrangement ofthe stationary drum side, a glass mask having a reflective portioncorresponding to only an effective recording area need only be arranged,and a mechanism of the scanner is simplified.

FIGS. 14A and 14B show a basis arrangement of a third arrangement of theselective switching device. FIG. 14A is a schematic sectional viewshowing a cylinder system, and FIG. 14B is a schematic plan view of thesystem. In this arrangement, as shown in FIG. 14B, photodetectors 20a,20b, 21a, and 21b for recording and reproduction are mounted in a rotarydrum 8 at positions corresponding to magnetic heads R1, R2, P1, and P2,respectively. In a stationary drum 9, if an angle of an effectiverecording area is 180°, a plurality of recording LEDs and reproductionLEDs are densely arranged in an arcuated pattern each within a rangecorresponding to the effective recording area in correspondence with thephotodetectors 20a, 20b, 21a, and 21b. In this embodiment, a pluralityof LEDs for recording and reproduction are recording and reproductionLED arrays 22 and 23.

A recording circuit is controlled by the recording LED array 22 at thestationary drum side, a reproduction circuit is controlled by thereproduction LED array 23, and the recording and reproduction LED arrays22 and 23 are controlled by a recording/reproduction controller 24. Thephotodetectors at the rotary drum side for directly controlling therecording and reproduction circuits in response to control light fromthe recording and reproduction LED arrays 22 and 23 are provided atpositions corresponding to recording and reproduction heads as shown inFIG. 14B. The photodetector 20a for controlling the recording circuit ofa magnetic head R1 is arranged at a position corresponding to themagnetic head R1, and the photodetector 20b for controlling therecording circuit of a magnetic head R2 at a position shifted from themagnetic head R1 by 180° is arranged at a position corresponding to themagnetic head R2. The photodetector 21a for controlling the reproductioncircuit of a magnetic head P1 is provided at a position corresponding tothe magnetic head P1, and the photodetector 21b for controlling thereproduction circuit of a magnetic head P2 at a position shifted fromthe magnetic head P1 by 180° is mounted in a position corresponding tothe magnetic head P2.

An operation of the above selective switching device will be describedbelow.

The rotary drum rotates in a direction indicated by an arrow shown inFIG. 14B, and the recording circuit of the magnetic head R1 iscontrolled by the photodetector 20a. That is, the recording circuit ofthe magnetic head R1 is set in an enable state while the photodetector20a opposes the recording LED array 22 corresponding to the recordingarea, and set in a disable state while the photodetector 20a passesthrough a region in which the recording LED array 22 is not present.Similarly, the recording circuit of the magnetic head R2 is controlledby the photodetector 20b. The reproduction circuit of the magnetic headP1 is controlled by the photodetector 21a. That is, the reproductioncircuit of the magnetic head P1 is set in an enable state while thephotodetector 21a opposes the reproduction LED array 23 corresponding tothe recording area, and set in a disable state while the photodetector21a passes through a region in which the reproduction LED array 23 isnot present. The reproduction circuit of the magnetic head P2 iscontrolled by the photodetector 21b. In this arrangement, thephotodetectors 20a, 20b, 21a, and 21b generate a 180° selection signalwhich can be input directly to the recording or reproduction circuit.

According to the above arrangement, in the stationary drum, since aplurality of LEDs corresponding to the effective recording area needonly be arranged, a mechanism of the cylinder system is simple.

Note that although an LED is used as a light-emitting element for use inrecording/reproduction control in each of the above arrangements,another light-emitting element such as an EL (electro-luminescence), asemiconductor laser, or a plasma display may be used.

In the above embodiment, a rotary drum type VTR has been described. Thepresent invention, however, can be applied to a VTR of a disc type or amedium drum type as another magnetic head mounting system.

In the above embodiment, switching is performed between a rotarytransformer having one channel and a recording or reproduction circuithaving two channels. Switching, however, can be similarly performed fora recording or reproduction circuit or a recording and reproductioncircuit having more channels. For example, if a recording head and arecording circuit have eight channels, a reproduction head and areproduction circuit have eight channels, and an effective recordingarea angle is 180°, a rotary transformer need only have eight channels.

As has been described above, by sequentially, selectively switching arecording or reproduction circuit or a recording and reproductioncircuit between enable and disable states. The number of channels of arotary transformer can be reduced to be 1/n (n=360/R: where R is theeffective recording area angle and n is a natural number) the number ofmagnetic heads and recording circuits, magnetic heads and reproductioncircuits, or magnetic heads and circuits for performing both recordingand reproduction.

Since n recording or reproduction circuits or n recording andreproduction circuits are sequentially, selectively switched betweenenable and disable state, power consumption of the circuits can bereduced. In addition, by reducing the number of channels of a rotarytransformer to be 1/n, a mechanism of a scanner portion can besimplified to improve reliability. As a result, the system can be madecompact and light in weight at a low manufacturing cost, and the numbersof driver circuits and receiver circuits of the rotary transformer canbe 1/n.

Furthermore, since the number of channels of the rotary transformer canbe reduced to be 1/n, inertia of a rotary drum is reduced to reduce aload on a rotary drum motor, and rotation of the rotary drum can reach astatic rotational speed within a short time period, thereby reducing atime required for starting transmission of an image.

As described above, the problems of the conventional apparatuses can besolved by commonly connecting recording or reproduction circuits orrecording and reproduction circuits, mounted together with magneticheads on a rotary drum, for performing recording or reproduction of aninformation signal to a rotary transformer, and sequentially,selectively switching the recording or reproduction circuits orrecording and reproduction circuits to an enable state in accordancewith a rotation position of the rotary drum.

The recording or reproduction circuits or recording and reproductioncircuits are arranged at different angular positions with respect to arotation angular direction of a rotary drum, i.e., a rotary member of arotary transformer. Therefore, if the circuits are commonly connected toa rotary transformer in which a single winding is provided in a singlewinding slot as in a conventional transformer, the position in arotation angular direction of lead wires of the rotary member of therotary transformer differs from that in a rotation angular direction ofthe circuits by a maximum of 180°. In this case, a circuit having alarger difference with respect to the position in the rotation angulardirection of the lead wires of the rotary member of the rotarytransformer requires a longer cable for coupling a driver or receivercircuit, i.e., the recording or reproduction circuits or recording andreproduction circuits, and the rotary transformer. Therefore, a couplingcapacitance between the driver or receiver circuit and the rotarytransformer is increased to degrade transmission characteristics. As aresult, a difference may be produced between characteristics of the nrecording or reproduction circuits or recording and reproductioncircuits.

For example, FIG. 15 shows an arrangement of a rotary transformerportion of one channel according to the above first embodiment in whichtwo recording heads R1 and R2 are arranged in positions shifted by 180°,FIG. 16 shows an arrangement of a rotary transformer portion of onechannel according to the above first embodiment in which tworeproduction heads P1 and P2 are arranged in positions shifted by 180°,an FIG. 17 shows a rotary transformer portion of one channel accordingto the above second embodiment in which a recording head R and areproduction head P are arranged in positions by 180°. As is apparentfrom FIGS. 15, 16, and 17, the length of wiring must be increased.

As described above, when circuits arranged in different directions withrespect to a rotation angular direction of a rotary member of a rotarytransformer are to be sequentially, selectively switched to an enablestate, the positions in rotation angular directions of the circuitsdiffer from the position in the rotation angular direction of the leadwires of the rotary member of the rotary transformer by a maximum of180°. Therefore, a circuit having a larger difference from the positionin the rotary angular direction of the lead wires of the rotary memberof the rotary transformer requires a longer cable for coupling withrespect to the driver or receiver circuit, thereby increasing a couplingcapacitance between the driver or receiver circuit and the rotarytransformer to degrade transmission characteristics. As a result, adifference may be produced between characteristics of the n recording orreproduction circuits or recording and reproduction circuits.

In an arrangement in which recording or reproduction circuits orcircuits for performing both recording and reproduction arranged indifferent directions with respect to a rotation angular direction of arotary member of a rotary transformer are sequentially, selectivelyswitched to an enable state, thereby reducing the number of channels ofthe rotary transformer, therefore, a rotary transformer apparatus can bearranged as follows in order to minimize a coupling capacitance betweena driver or receiver circuit and the rotary transformer and to minimizea difference between characteristics of the recording or reproductioncircuit or recording and reproduction circuits.

That is, by arranging a plurality of windings in a single winding slotof a rotary member, a stationary member, or both the rotary andstationary members, a lead position of lead wires of each of a pluralityof windings arranged in a single slot can be arranged to coincide withthe position of a corresponding recording or reproduction circuit orrecording and reproduction circuit in the rotation angular direction ofthe rotary transformer. In addition, a circuit for setting a highimpedance in an output stage of each of n reproduction circuits commonlyconnected in parallel with the above rotary transformer in a disablestate may be provided to prevent the reproduction circuit in a disablestate from adversely affecting another circuit.

FIG. 18 is a plan view showing a rotary member of a rotary transformerapparatus according to the third to fifth embodiments of the presentinvention. An arrangement in which an effective recording area angle is180° will be described. Two windings 33a and 33b are wound around awinding slot 32 annularly formed in a ferrite core 31. Lead wires 34aand 34b of the two windings 33a and 33b, respectively, are led atpositions having entirely different rotation angular directions(positions shifted by 180° in FIG. 18) of a rotary transformer.

FIG. 19 shows an arrangement in which a rotary transformer apparatus 42of the third embodiment of the present invention comprising a rotarymember (rotor) 35 having the arrangement shown in FIG. 20 and astationary member (stator) 36 in which a single winding is wound in awinding slot is used for recording. An information signal (RF signal) tobe recorded in a magnetic tape is amplified by a rotary transformerdriving circuit 40 and transmitted into a rotary drum via the rotarytransformer apparatus 42. Two magnetic heads R1 and R2 are arranged atpositions shifted by 180°. Recording circuits 41a and 41b connected tothe two magnetic heads R1 and R2, respectively, are arranged atpositions in the rotary drum shifted by 180° so as to minimize a cablelength to obtain a minimum connection capacitance. Note that the RFsignal to be input to the rotary transformer driving circuit 40 includesboth information signals to be recorded by the magnetic heads R1 and R2and these signals must be transmitted to the heads R1 and R2 withminimum degradation in characteristics. One recording circuit 41a,therefore, is connected to the lead wires 34a from the first windingwound in the winding slot of the rotary member 35, and the otherrecording circuit 41b is connected to the lead wires 34b from the secondwinding wound in the winding slot of the rotary member 35. A winding 37provided in a slot formed in the stationary member 36 is positioned atsubstantially the central portion between the two windings 33a and 33bprovided in the rotary member 35 opposing the stationary member 36. Withthis arrangement, since the lead wires 34a and 34b are arranged in therotary drum to oppose each other with an angle of 180° therebetween,connection distances from the recording circuits 41a and 41b to thewindings 33a and 33b, respectively, can be minimized. Therefore, acoupling capacitance between the circuits and the rotary transformer anda difference between the two recording circuits can be minimized. Therecording circuits 41a and 41b are sequentially switched between enableand disable states upon each 180° rotation by R1 and R2 selectionsignals, respectively. When the recording circuit is in the enablestate, the magnetic head R1 or R2 is driven to record an RF signal in amagnetic tape (not shown).

In this arrangement, signal transmission is alternately performedbetween the windings 37 and 33a and between the windings 37 and 33b eachtime the rotary drum rotates through 180°. If, however, an inputimpedance of the recording circuit 41b is low while a signal istransmitted between the windings 37 and 33a or an input impedance of therecording circuit 41a is low while a signal is transmitted between thewindings 37 and 33b, transmission characteristics are degraded. Theinput impedance of the recording circuit 41b, therefore, must be highwhile a signal is transmitted between the windings 37 and 33a, and theinput impedance of the recording circuit 41a must be high while a signalis transmitted between the windings 37 and 33b. For this purpose, anemitter follower or a Darlington emitter follower is used as a circuitat an input stage of each of the recording circuits 41a and 41b so asnot to cause degradation in transmission characteristics, therebyincreasing the input impedance.

FIG. 20 shows a series of time sequences of a switching operation of therecording circuits.

The recording circuits 41a and 41b are sequentially switched betweenenable and disable states upon each 180° rotation by the R1 and R2selection signals, respectively. When the recording circuits 41a and 41bare in an enable state, input RF signals drive the magnetic heads R1 andR2 to supply R1 and R2 recording currents to the magnetic heads,respectively. As a result, the RF signals corresponding to the currentsare recorded in a magnetic tape.

FIG. 21 shows the fourth embodiment of the present invention in which arotary transformer apparatus 42 comprising a rotary member 35 having thearrangement as shown in FIG. 18 and a stationary member 36 in which asingle winding is wound in a winding slot is used for reproduction.

RF signals reproduced from a magnetic tape by magnetic heads P1 and P2are amplified by reproduction circuits 43a and 43b, respectively. Therotary transformer apparatus 42 is driven by outputs from thereproduction circuits 43a and 43b to transmit the reproduced RF signalsoutside a rotary drum. As is apparent from a series of time sequences ofa switching operation of the reproduction circuits shown in FIG. 22, thereproduction circuits 43a and 43b are sequentially switched betweenenable and disable states upon each 180° rotation by P1 and P2 selectionsignals, respectively. When the reproduction circuit is in an enablestate, an RF signal obtained from a P1 or P2 reproduced signalreproduced from the magnetic head P1 or P2, respectively, is transmittedoutside the rotary drum. The reproduced RF signal is received by arotary transformer receiving circuit 44 and transmitted to a circuit ata subsequent stage.

In this arrangement, the two magnetic heads P1 and P2 are arranged inpositions shifted by 180°. In order to minimize a cable length to obtaina minimum connection capacitance, the two reproduction circuits 43a and43b connected to the magnetic heads P1 and P2, respectively, arearranged in the rotary drum to oppose each other with an angle of 180°therebetween. An RF signal to be input to the rotary transformerreceiving circuit 44 must include both information signals to bereproduced by the magnetic heads P1 and P2, and these signals must betransmitted from the heads P1 and P2 with minimum degradation incharacteristics. One reproduction circuit 43a, therefore, is connectedto lead wires 34a of a first winding 33a wound in a winding slot of therotary member 35, and the other reproduction circuit 43b is connected tolead wires 34b of a second winding 33b wound in a winding slot of therotary member 35. With this arrangement, since the lead wires 34a and34b are arranged at positions in the rotary drum shifted by 180°,connection distances from the reproduction circuits 43a and 43 b to thewindings 33a and 33b of the rotary transformer, respectively, can beminimized. Therefore, a coupling capacitance between the circuits andthe rotary transformer and a difference between the two circuits can beminimized. The reproduction circuits 43a and 43b are sequentiallyswitched between enable and disable states upon each 180° rotation by P1and P2 selection signals, respectively. A reproduction circuit in anenable state drives the magnetic head P1 or P2 to reproduce an RF signalfrom the magnetic head.

Outputs from the reproduction circuits 43a and 43b are connected to thesame rotary transformer apparatus 42. Therefore, in order to preventdegradation in frequency characteristics in a reproduction circuit in anenable state, an output from a reproduction circuit in a disable stateis set in a high-impedance state. For this purpose, a circuit similar tothat shown in FIG. 4 is used to increase the impedance of an output fromthe reproduction circuit. Note that although only one output side isshown in FIG. 4, outputs form the reproduction circuits are paralleloutputs.

FIG. 23 shows the fifth embodiment of the present invention in which arotary transformer apparatus 42 comprising a rotary member 35 having thearrangement as shown in FIG. 18 and a stationary member 36 in which asingle winding is wound in a winding slot is used for both recording andreproduction. In this embodiment, recording and reproduction arealternately performed each time the rotary drum rotates through 180°.

A recording circuit 45 amplifies an information signal from the rotarytransformer apparatus 42 and supplies the amplified signal to a magnetichead R, thereby driving the head R. A magnetic head P is arranged in aposition shifted by 180° from the magnetic head R. The informationsignal is reproduced from a magnetic tape by the magnetic head P,amplified by a reproduction circuit 46, and transmitted outside therotary drum by the rotary transformer apparatus 42 connected to theoutput side of the reproduction circuit 46. An information signal (RFsignal) to be recorded in the magnetic tape is amplified by a rotarytransformer driving circuit 47 and transmitted into the rotary drum bythe rotary transformer apparatus 42. As is apparent from a series oftime sequences of a switching operation of the recording andreproduction circuits shown in FIG. 24, the recording circuit 45 issequentially switched between enable and disable states upon each 180°rotation by an R selection signal. When the recording circuit is in anenable state, it drives the magnetic head R by an R recording current torecord the RF signal in the magnetic tape.

Reproduction of an RF signal from a magnetic tape will be describedbelow. An RF signal reproduced from a magnetic tape by the magnetic headP is amplified by the reproduction circuit 46 to drive the rotarytransformer apparatus 42. The rotary transformer apparatus 42 transmitsthe RF signal outside the rotary drum. As is apparent from a series oftime sequences of the switching operation of the recording andreproduction circuits shown in FIG. 26, the reproduction circuit 46 issequentially switched between enable and disable states upon each 180°rotation by a P selection signal. When the reproduction circuit is in anenable state, it transmits a reproduced output as an RF signalreproduced by the magnetic head P to outside the rotary drum. Thereproduced RF signal transmitted from the apparatus 42 is received by arotary transformer receiving circuit 48 and transmitted to a circuit ata subsequent stage.

In this arrangement, the two magnetic heads R and P are arranged inpositions shifted by 180°. In order to minimize a cable length to obtaina minimum connection capacitance, the recording and reproductioncircuits 45 and 46 connected to the two magnetic heads are arranged inthe rotary drum at positions shifted by 180°. These signals must betransmitted from an RF signal input to the magnetic head R uponrecording and from the magnetic head P to an RF signal output uponreproduction with minimum degradation in characteristics. The recordingcircuit 45, therefore, is connected to lead wires 34b of a secondwinding 33b wound in a winding slot of the rotary member 35, and thereproduction circuit 46 is connected to lead wires 34a of a firstwinding 33a wound in a winding slot of the rotary member 35. With thisarrangement, since the lead wires 34a and 34b are arranged at positionsin the rotary drum shifted by 180°, a connection distance from therecording circuit 45 to the winding 33b of the rotary transformer andthat from the reproduction circuit 46 to the winding 33a of the rotarytransformer can be minimized. As a result, a coupling capacitancebetween the circuits and the rotary transformer can be minimized toachieve minimum degradation in characteristics.

In this arrangement, the recording and reproduction circuits 45 and 46are connected to the same rotary transformer apparatus 42. In order toprevent degradation in frequency characteristics of a circuit in anenable state, therefore, an input of the recording circuit in a disablestate and an output of the reproduction circuit in a disable state areset in a high-impedance state. A method of obtaining a high impedance isthe same as that of the above two embodiments.

In each of the above third to fifth embodiments, an arrangement in whichthe above technique is applied to only a rotary member has beendescribed by taking a flat type one-channel rotary transformer apparatusas an example. The above technique, however, can be applied to astationary member. In addition, the above technique can be applied alsoto a coaxial type rotary transformer apparatus. Furthermore, the abovetechnique can be applied regardless of the number of channels or thenumber of turns of a winding of a rotary transformer apparatus.

In a rotary transformer apparatus as described above, transmissioncharacteristics may be changed due to rotation of a rotary drum, i.e.,rotation of a rotary transformer. Such a change in transmissioncharacteristics significantly appears when the number of turns of awinding is small and is most conspicuous when a winding has only oneturn. Since the number of turns of a winding must be reduced as thefrequency of a transmission signal is increased, the number of turns isreduced as the band and transmission rate of a VTR using the rotarytransformer are widened and increased, respectively.

For example, an arrangement in which windings 53 and 54 each having oneturn are wound in a winding slot of one member (one of stationary androtary members) 51 of a rotary transformer and a winding 55 having oneturn is wound in a winding slot of the other member 52 as shown in FIGS.25 and 26 will be described below.

Referring to FIG. 25, the one-turn winding 55 of the member 52 is woundin a central portion of the winding slot. With this arrangement, it isassumed that transmission characteristics between the windings 53 and 54wound around the member 51 and the winding 55 wound around the member 52are substantially equal to each other provided that the members and thewindings are ideally arranged. Actually, however, it is impossible towind, e.g., the winding 55 in the central portion of the winding slotthroughout 360°. Upon rotation, therefore, transmission characteristicsbetween the windings 53 and 55 or windings 54 and 55 are changed.

As shown in FIG. 26, the one-turn winding 55 of the member 52 may beshifted to one side of the winding slot. In this case, a change intransmission characteristics caused upon rotation between the opposingwindings 54 and 55 can be reduced to a negligible level. A change intransmission characteristics between the windings 53 and 55 which do notoppose each other, however, is caused more easily than when the winding55 is wound in the central portion of the winding slot. In addition, alarge difference is produced between the transmission characteristicsbetween the windings 53 and 55 and those between the windings 54 and 55.When the rotary transformer is used, the windings 53 and 54 areselectively used. It is, therefore, not preferred that a difference isproduced between the transmission characteristics between the windings53 and 55 and those between the windings 54 and 55.

As described above, in a rotary transformer apparatus for transmittingsignals between rotary and stationary members, in which a plurality ofwindings are arranged in a single slot of the rotary member and a singlewinding is arranged in a slot of the stationary member or a plurality ofwindings are arranged in a single slot of the stationary member and asingle winding is arranged in a slot of the rotary member, transmissioncharacteristics between a plurality of transmission paths arepreferably, constantly uniform.

In the embodiments of the present invention, therefore, the thickness orwidth of a winding of a member in which a single winding is arranged isincreased to be larger than that of each of a plurality of windings of amember in which a plurality of windings are arranged, thereby obtainingconstantly uniform transmission characteristics between a plurality oftransmission paths. As described above, this method is most effectivewhen a winding has only one turn. In each of the following embodiments,therefore, an arrangement in which two one-turn windings are woundaround one member and single one-turn winding is wound around the othermember will be described.

FIG. 27 schematically shows a rotary transformer apparatus used in thesixth embodiment of the present invention.

In this embodiment, a winding 56 of a member 52 is constituted by a wirethicker than that of windings 53 and 54 of a member 51 and wound in awinding a slot of the member 52 so that a portion corresponding to 1/2of a wire diameter projects from the slot. When an opposing surface S ofthe member 52 with respect to the member 51 is polished, the winding 56is simultaneously polished to obtain a semicircular section. Since thepolished surface of the winding 56 uniformly opposes the windings 53 and54, no difference is produced between transmission characteristicsbetween the windings 53 and 56 and those between the windings 54 and 56,and a change in transmission characteristics caused upon rotation can besuppressed.

FIG. 28 schematically shows a rotary transformer apparatus used in theseventh embodiment of the present invention.

In this embodiment, since a winding 57 of a member 52 is constituted bya metal foil such as a copper foil. no difference is produced betweentransmission characteristics between windings 53 and 57 and thosebetween windings 54 and 57, and a change in transmission characteristicscaused upon rotation can be suppressed. In this arrangement, the metalfoil is fixed on a member by an adhesive or the like.

FIG. 29 schematically shown a rotary transformer apparatus used in theeighth embodiment of the present invention.

In this embodiment, since a winding 58 of a member 52 is constituted bya metal plate, no difference is produced between transmissioncharacteristics between windings 53 and 58 and those between windings 54and 58, and a change in transmission characteristics caused uponrotation can be suppressed. In this arrangement, the metal plate isformed to have a shape corresponding to the shape of a winding slot andthen fitted in the slot. If, however, the member 52 consists of aconductor, a problem may be posed in characteristics unless the member52 and the winding 58 are electrically insulated from each other.

FIG. 30 schematically shows a rotary transformer apparatus used in theninth embodiment of the present invention which solves the above problemof insulation.

In this embodiment, since a winding 59 of a member 52 is constituted bya printed wiring board composed of an insulating plate 59A and aconductor foil 59B, no difference is produced between transmissioncharacteristics between windings 53 and 59 and those between windings 54and 59, and a change in transmission characteristics caused uponrotation can be suppressed. In this arrangement, although not shown inFIG. 32, two side portions of the conductor foil 59B are not in directcontact with the inner walls of a winding slot of the member 52, therebyelectrically insulating the member 52 and the winding 59 from eachother.

FIG. 31 schematically shows a rotary transformer apparatus used in thetenth embodiment of the present invention.

In this embodiment, since a winding 60 of a member 52 is formed bydeposition of a conductive metal, no difference is produced betweentransmission characteristics between windings 53 and 60 and thosebetween windings 54 and 60, and a change in transmission characteristicscaused upon rotation. In this arrangement, in order to electricallyinsulate the member 52 and the winding 60 from each other, an insulatingmaterial is preferably deposited before deposition of the metal.Alternatively, the winding 60 can be formed not by deposition but by,e.g., sputtering.

FIG. 32 schematically shows a rotary transformer apparatus used in the11th embodiment of the present invention. FIG. 33 is a top view of amember 52 shown in FIG. 32.

In this embodiment, since a winding 61 of a member 52 is constituted bytwo windings 62 and 63 connected in parallel with each other toelectrically form one turn, no difference is produced betweentransmission characteristics between windings 53 and 61 and thosebetween windings 54 and 61, and a change in transmission characteristicscaused upon rotation can be suppressed. The windings 62 and 63 areconnected with each other at a lead port 64 and connected to externalcircuits via lead wires 65 and 66, respectively, of the rotarytransformer.

In each of the above embodiments, the present invention has beendescribed by taking a flat type one-channel rotary transformer as anexample. The present invention, however, can be applied to a coaxialtype rotary transformer apparatus. In addition, the present inventioncan be applied regardless of the number of channels of a rotarytransformer apparatus.

In addition, in a rotary transformer apparatus for transmitting signalsbetween a rotary member having a plurality of windings wound in a singleslot and a stationary member having a single winding wound in a slot orbetween a stationary member having a plurality of windings wound in asingle slot and a rotary member having a single winding wound in a slot,uniformity of transmission characteristics can be increased by setting awinding slot width of a member having a single winding to be differentfrom that of a member having a plurality of windings.

For example, the width of a winding slot of a member having a singlewinding is set to be larger than that of a member having a plurality ofslots so that a thicker (larger diameter) or wider winding can be woundAs a result, since a single winding and a plurality of windings opposeeach other more easily, uniformity of transmission characteristics of aplurality of transmission paths can be improved.

With this arrangement, a core width of a member having a wider windingslot width can be made smaller than that of a member having a narrowerwinding slot width. Therefore, since a core opposing width is defined bythe core width of the member having a wider winding slot width, aninfluence of variation caused by rotation can be reduced.

FIGS. 34 to 45 show arrangements of rotary transformer apparatusesaccording to the 12th to 23rd embodiments of the present inventionobtained by adopting the above technique to the embodiments shown inFIGS. 29 to 34, respectively.

In these embodiments, similar to the embodiments shown in FIGS. 27 to32, the effect of the present invention is remarkable when a winding iswound by one turn. In each of the following embodiments, therefore, anarrangement in which two one-turn windings are wound in one member andone one-turn winding is wound in the other member will be described.

FIGS. 34 and 35 schematically show rotary transformer apparatusesaccording to the 12th and 13th embodiments of the present invention,respectively.

These embodiments differ from the embodiment shown in FIG. 27 in that awinding slot width 76 of a member 52 is made wider than a winding slotwidth 77 of a member 51. With this arrangement, a winding 56' of themember 52 can be made thicker than the winding 56 shown in FIG. 29 andtherefore can be easily opposed both windings 53 and 54 of the member51. In addition, since a core width 79 of the member 52 can be madesmaller than a core width 78 of the member 51, a variation in coreopposing area can be suppressed. Although only the winding slot width ischanged in FIG. 36, the outer diameter of the member 52 can be madesmaller than that of the member 51 as shown in FIG. 37. In this case,since the core opposing area is defined by core width of member 52×(coreouter diameter of member 52+core inner diameter of member 52)/2, avariation caused by rotation can be further reduced. As a result, achange in transmission characteristics caused by rotation can besuppressed.

FIGS. 36 and 37 schematically show rotary transformer apparatusesaccording to the 14th and 15th embodiments of the present invention,respectively.

These embodiments differ from the embodiment shown in FIG. 28 in than awinding slot width 76 of a member 52 is made wider than a winding slotwidth 77 of a member 51. With this arrangement, a thin film 57' used asa winding of the member 52 can be made wider than the thin film 57 shownin FIG. 28 and therefore can be easily opposed both windings 53 and 54of the member 51. In addition, since a core width 79 of the member 52can be made smaller than a core width 78 of the member 51, a variationin core opposing area can be suppressed. Although only the winding slotwidth is changed in FIG. 36, the outer diameter of the member 52 can bemade smaller than that of the member 51 as shown in FIG. 37. In thiscase, since the core opposing area is defined by core width of member52×(core outer diameter of member 52+core inner diameter of member52)/2, a variation caused by rotation can be further reduced. As aresult, a change in transmission characteristics caused by rotation canbe suppressed.

FIGS. 38 and 39 schematically show rotary transformer apparatusesaccording to the 16th and 17th embodiments of the present invention,respectively.

These embodiments differ from the embodiment shown in FIG. 29 in that awinding slot width 76 of a member 52 is made wider than a winding slotwidth 77 of a member 51. With this arrangement, a metal plate 58' usedas a winding of the member 52 can be made wider than the metal plate 58shown in FIG. 29 and therefore can be easily opposed both windings 53and 54 of the member 51. In addition, since a core width 79 of themember 52 can be made smaller than a core width 78 of the member 51, avariation in core opposing area can be suppressed. Although only thewinding slot width is hanged in FIG. 38, the outer diameter of themember 52 can be made smaller than that of the member 51 as shown inFIG. 39. In this case, since the core opposing area is defined by corewidth of member 52×(core outer diameter of member 52+core inner diameterof member 52)/2, a variation caused by rotation can be further reduced.As a result, a change in transmission characteristics caused by rotationcan be suppressed.

FIGS. 40 and 41 schematically show rotary transformer apparatusesaccording to the 18th and 19th embodiments of the present invention,respectively.

These embodiments differ from the embodiment shown in FIG. 30 in that awinding slot width 76 of a member 52 is made wider than a winding slotwidth 77 of a member 51. With this arrangement, a printed wiring board59' used as a winding of the member 52 can be made wider than theprinted wiring board 59 shown in FIG. 30 and therefore can be easilyopposed both windings 53 and 54 of the member 51. In addition, since acore width 79 of the member 52 can be made smaller than a core width 78of the member 51, a variation in core opposing area can be suppressed.Although only the winding slot width is changed in FIG. 40, the outerdiameter of the member 52 can be made smaller than that of the member 51as shown in FIG. 41. In this case, since the core opposing area isdefined by core width of member 52×(core outer diameter of member52+core inner diameter of member 52)/2, a variation caused by rotationcan be further reduced. As a result, a change in transmissioncharacteristics caused by rotation can be suppressed.

FIGS. 42 and 43 schematically show rotary transformer apparatusesaccording to the 20th and 21st embodiments of the present invention,respectively.

These embodiments differ from the embodiment shown in FIG. 31 in that awinding slot width 76 of a member 52 is made wider than a winding slotwidth 77 of a member 51. With this arrangement, a deposited or sputteredfilm 60' used as a winding of the member 52 can be made wider than thedeposited or sputtered film 60 shown in FIG. 31 and therefore can beeasily opposed both windings 53 and 54 of the member 51. In addition,since a core width 79 of the member 52 can be made smaller than a corewidth 78 of the member 51, a variation in core opposing area can besuppressed. Although only the winding slot width is changed in FIG. 42,the outer diameter of the member 52 can be made smaller than that of themember 51 as shown in FIG. 43. In this case, since the core opposingarea is defined by core width of member 52×(core outer diameter ofmember 52+core inner diameter of member 52)/2, a variation caused byrotation can be further reduced. As a result, a change in transmissioncharacteristics caused by rotation can be suppressed.

FIGS. 44 and 45 schematically show rotary transformer apparatusesaccording to the 22nd and 23rd embodiments of the present invention,respectively.

These embodiments differ from the embodiment shown in FIG. 32 in that awinding slot width 76 of a member 52 is made wider than a winding slotwidth 77 of a member 51. With this arrangement, a (double) winding 61'used as a winding of the member 52 can be made wider than the (double)winding 61 shown in FIG. 32 and therefore can be easily opposed bothwindings 53 and 54 of the member 51. In addition, since a core width 79of the member 52 can be made smaller than a core width 78 of the member51, a variation in core opposing area can be suppressed. Although onlythe winding slot width is changed in FIG. 44, the outer diameter of themember 52 can be made smaller than that of the member 51 as shown inFIG. 45. In this case, since the core opposing area is defined by corewidth of member 52×(core outer diameter of member 52+core inner diameterof member 52)/2, a variation caused by rotation can be further reduced.As a result, a change in transmission characteristics caused by rotationcan be suppressed.

The following is the description of an embodiment designed so thatdisconnection will hardly occur between a metal wiring film in a slotand lead wires by integrally forming, by means of etching ordie-cutting, the wiring film in the slot and the lead wire of a rotarytransformer to transmit signals between rotary member and stationarymember.

In FIG. 46, the winding of a rotary transformer device has the wireportion 101 in the core slot and the lead-wire portion 102, which areintegrally formed by etching or die-cutting. Under the state shown inFIG. 46, it is difficult to lead the lead wire to the outside of therotary transformer and electrically connect them with an externalcircuit.

Therefore, as shown in FIG. 47, the lead wire is let to the outside ofthe rotary transformer and electrically connected to the externalcircuit by folding the lead-wire portion 102. In this case, the foldingposition is determined according to the position and shape of theleading hole or slot of the rotary transformer.

FIG. 48 shows an embodiment in which the present invention is applied toa coaxial-type rotary transformer. The portions 101 and 102 in FIG. 48correspond to the portions 106 and 107 in FIG. 47 respectively. Thewinding 101 is wound in the slot 107 of the core 106. The lead wire 102integrally formed with the winding 101 by etching or die-cutting is ledto the outside of the rotary transformer through lead-wire hold 108 ofthe core 106 and the lead-wire slot 110 formed on the housing 109 towhich the core 106 is secured.

In this case, the portion 11 is folded according to the shapes of thecore 106 and the housing 109.

Therefore, the wire in the slot can be formed so that the metal platewill be integrated with the leading portion.

However, because the lead-wire portion 102 in FIG. 48 is exposed unlikethe case of using a general enameled wire, two lead wires mayelectrically contact each other and either or both of the winding mayelectrically contact the housing 111.

The contacting possibility is the highest at the folding portion.Therefore, the lead-wire portion 102 is covered with the insulationcoating 112 by dipping it in, for example, varnish. Thus, two lead wiresdo not electrically contact each other and either or both of thewindings do not electrically contact the housing 111.

The insulation coating can be realized by various types of insulationprocessings with enamel or epoxy as well as varnish. It is also possibleto simply cover the lead wire with an insulating tube or heat-shrinkabletube.

FIG. 50 shows a flat-type rotary transformer to which the presentinvention is applied. In FIG. 50, the winding 101 is wound in the slot107 of the core 106 and the lead wire 102 integrally formed with thewinding 101 by etching or die-cutting is folded at the lead-wire hole108 of the core 106 and led to the outside of the rotary transformer.

In this case, the lead wire is folded at the housing according to theposition of the hole on the core 106. Therefore, the wire in the slot isintegrated with the metal plate and leading portion. The winding andlead wire integrally formed by etching or die-cutting can be not onlyformed into the structure shown in FIG. 46 but formed of the circularconductor 101 and the straight conductor 102 extended form the circularconductor 101 as shown in FIG. 51 or the circular conductor 101 and thestraight conductor 102 extended into the circular conductor 101 as shownin FIG. 52, depending on the shape of the rotary transformer.

FIG. 53 shows a coaxial-type rotary transformer provided with doublewinding. In the rotary transformer, the double winding 101 is wound atthe top and bottom stages in the slot 107 of the core 106 and the leadwire 102 integrally formed with the double winding 101 by etching ordie-cutting is led to the outside of the rotary transformer through thelead wire hole 108 of the core 106 and the lead wire slot 11 formed onthe housing 109 where the core 106 is secured.

In this case, the portion 111 is folded according to the shapes of thecore 106 and housing 109. The present invention can be applied to therotor or stator of the coaxial-type rotary transformer provided withsaid double winding.

In the above embodiment, the present invention is described by taking anone-channel rotary transformer as an example. However, the presentinvention can be applied to various types of rotary transformersregardless of the number of channels.

The following is the description of a magnetic recording/reproductionapparatus having an erasing circuit, in which the erasing frequencycharacteristic is hardly degraded, the number of channels of a rotarytransformer can be decreased, the power consumption of the erasingcircuit mounted on a rotary drum can be decrease, and a scannermechanism can be simplified and compacted.

This embodiment describes an apparatus having the magnetic-tape lapangle of 180° and comprising two erasing circuits.

In FIG. 54, the magnetic tape 122 is wound on the circumferentialsurface of the rotary drum of the scanner 121 so that the effectiverecording area of the magnetic tape 122 will be 180°. To record data,the recording circuit 123a amplifies the information signal sent fromthe rotary transformer and drives the recording magnetic head R1according to the information signal.

The recording magnetic head R2 is installed at the position 180° apartform the recording magnetic head R1 and drive by the recording circuit123b.

To reproduce data, the reproduction magnetic head P1 reproduces theinformation signal from the magnetic tape and the information signal isamplified by the reproduction circuit 124a.

The reproduction magnetic head P2 is installed at the position 180°apart from the reproduction magnetic head P1 and the information signalreproduced by the magnetic tape is amplified by the reproduction circuit124b through the reproduction magnetic head P2.

Reproduced information signals are transmitted to the outside of therotary drum by the rotary transformer connected to the output terminalsof the reproduction circuits 124a and 124b.

To erase data, the erasing circuit 125a amplifies the erasing signalsent from the rotary transformer to supply the amplified erasing signalto the erasing magnetic head E1.

The erasing magnetic head E1 is driven by the erasing signal in order toerase recorded information.

The erasing magnetic head E2 is installed at the position 180° apartfrom said erasing magnetic head E1.

The erasing magnetic head E2 is connected to the erasing circuit 125band driven to erase the recorded information with the erasing signalamplified by the erasing circuit 125b.

The following is the description of the operations of the erasingcircuits 125a and 125b according to FIGS. 55 and 56.

To control the information signal recorded in a magnetic tape by therecording magnetic heads R1 and R2, the erasing signal is the rotarytransformer driver circuit 126 and transmitted to an internal circuit ofthe rotary drum by the rotary transformer 127.

In this case, the erasing signal input to the rotary transformer drivercircuit 126 contains the erasing signal for both the erasing magneticheads E1 and E2.

The input terminals of the erasing circuits 125a and 125b are connectedto the secondary windings 127a and 127b of the rotary transformer 127,respectively.

The erasing circuits 125a and 125b are alternately switched to theactive state and non-active state by the E1 and E2 switching signalsevery 180°, supplying the erasing signal to the erasing magnetic headsE1 and E2 in order to erase the information signal in the magnetic tapeunder the active state.

The following is the description of the erasing circuit to decrease thenumber of rotary transformer channels.

The input stage of an erasing circuit is configured as an emitterfollower or Darlington emitter follower circuit so that frequencycharacteristics will not be degraded when input terminals of the erasingcircuits 125a and 125b are connected to the output terminal of therotary transformer in common. Therefore, the input impedance is sethigh.

By increasing the input impedance of an erasing circuit, damping isapplied to frequency characteristics to prevent them from degradation.

Because the input capacity of the emitter follower is normally small,degradation of frequency characteristics does not matter. The followingis the description of a 4-channel erasing circuit according to FIGS. 57through 59.

FIG. 57 shows a magnetic recording/reproduction apparatus to operate a4-channel erasing circuit with one rotary transformer, in which themagnetic-tape lap angle is set to 240°, that is, the magnetic tape 12 iswound on the circumferential surface of a rotary drum so that theeffective recording area of information signals will be 240°.

FIG. 58 shows the circuit configuration of the erasing circuit in FIG.56. FIG. 59 shows a series of time charts for describing the switchingoperation of an erasing circuit. In FIG. 57, recording and reproductioncircuits are omitted. In this embodiment, the erasing signal for erasingthe recording signal in the magnetic tape 122 is input to the rotarytransformer driver circuit 126 from the outside of the scanner 1,amplified, and transmitted to the internal circuit of a rotary drumthrough the rotary transformer 127.

The secondary windings 127a through 127d of the rotary transformer 127are connected to the input terminals of the erasing circuits 125athrough 125d, respectively to transmit the erasing signal to eacherasing circuit. When the erasing signal is input to the erasingcircuits 125a through 125d via the rotary transformer 127, the erasingsignal is amplified by the erasing circuit and supplied to the erasingheads E1 through E4 respectively connected to the output terminals ofthe erasing circuits 125a through 125d.

Therefore, the erasing head is driven by the erasing signal in order toerase the information signal recorded in the magnetic tape 122.

The erasing circuits 125a through 125d are alternately switched toactive state and non-active state by the E1 through E4 switching signalsto be mentioned later respectively.

In this embodiment, the magnetic tape is wound on the rotary drum withthe lap angle of 240° and 4-channel erasing circuits are selectivelyoperated.

In this case, thought several erasing circuits are operated, thefrequency characteristics of the recording/reproduction apparatus arenot degraded by increasing the input impedance of the erasing circuits.

Because erasing signals have a single frequency, there is no problem inerasing if signals with the frequency can adequately be transmitted toerasing circuits. That is, problems are eliminated from erasing ifdegradation of frequency characteristics caused by connecting severalerasing circuits in parallel is compensated by a rotary transformerdriver circuit.

The following is the description of the method and circuit toalternately switch an erasing circuit to active state and non-activestate according to FIGS. 60A, 60B, 61, and 62.

In the embodiment shown in FIGS. 60A and 60B, the magnetic-tape lapangle is set to 180° and two erasing heads are installed at the position180° apart from each other.

The rotary drum 128 faces the stationary drum 129 as shown in FIG. 60A.

The erasing circuit is controlled by the LED (light emitting diode) 131installed on the stationary drum and the erasing control circuit 130 tocontrol the LED 131.

That is, the erasing circuit is controlled by the detection signal bythe fact that the control beam emitted from the LED 131 is detected bylight-detecting elements or the photodetectors 132 and 132b installed onthe rotary drum 128 respectively facing the erasing heads E1 and E2which are installed at the position 180° apart from each other and thedetection signal is supplied to the erasing circuit.

In FIGS. 60A and 60B, the LED 131 is turned on by the erasing controlcircuit 130 and the rotary drum 128 rotates in the direction of thearrow. When the position of the photodetector 132a coincides with thatof the erasing LED 131, the photodetector 132a outputs Hi-level signals.

Because the output terminal of the photodetector 132a is connected tothe set input terminal of the flip-flop circuit 133 as shown in FIG. 61,the flip-flop circuit 133 outputs Hi-level signals through the outputterminal Q.

when the photodetector 132a separates from the LED 131 after the rotarydrum 128 further rotates in the direction of the arrow, the output ofthe photodetector 132 goes Lo-level. When the rotary drum 128 furtherrotates in the direction of the arrow and the photodetector 132bconnected to the reset input terminal of the flip-flop circuit 133detects the beam emitted from the LED 131, the flip-flop circuit 133 isreset and the output of the terminal Q of the flip-flop circuit 133 goesLo-level.

Similarly, whenever the rotary drum 128 rotates 180°, the output of theflip-flop circuit 133 alternately goes Hi-level and Lo-level.

The output of the terminal Q brings the erasing circuit E1 under activestate in Hi level and under non-active state in Lo level. Also, theoutput of the terminal Q brings the erasing circuit E2 under activestate in Hi level and under non-active state in Lo level. (See FIG. 62.)

As mentioned above, in this embodiment, the circuit system at the rotaryand stationary drum side can be composed of simple circuits and thepower consumption of the erasing circuit mounted on the rotary drum canbe decreased.

In this embodiment, the erasing LED 131 is turned on when VTR is in theerasing mode and turned off when it is in other mode. The following isthe description of the switching circuit of another embodiment.

In this embodiment, the reflection-type photosensors 134a and 134b areinstalled on the rotary drum 128 so that they will face the erasingmagnetic heads E1 and E2 respectively.

For the effective recording area of 180°, a reflector (e.g. a mirror) isinstalled at the erasing side and a non-reflector at the non-erasingside.

The reflection-type photosensors 134a and 134b are configured byintegrating the LED 135 with the photodiode or phototransistor 136 asshown in FIG. 64.

It is assumed that this embodiment uses the reflection-type photosensorto output Hi-level signals when it faces the reflector and Lo-levelsignals when it faces the non-reflector. The erasing circuit is inactive state while the rotary drum 128 rotates in the direction of thearrow, the erasing circuit corresponding to the erasing head E1 iscontrolled by the reflection-type photosensor 134a, and the photosensor134b passes through the erasing area where the reflector is installed.Similarly, the erasing circuit corresponding to the erasing head E2 iscontrolled by the reflection-type photosensor 134b. As mentioned above,the switching signal to be directly input to the erasing circuit by thereflection-type photosensors 134a and 134b can be generated according tothis embodiment. Switching is executed by, for example, a slip ring.

Moreover, the control circuit at the rotary drum side is very simplyconfigured which is able to control the circuit mounted on the rotarydrum and decrease power consumption.

If the stationary drum uses, for example, a glass mask with a reflectionsurface only for the effective recording area, the control mechanism canbe simplified.

The following is the description of a switching circuit used for anotherembodiment according to FIGS. 65A and 65B.

In this embodiment, the photodetectors 137a and 137b to control erasingcircuits are installed on the rotary drum 128 so that they will face theerasing heads E1 and E2 respectively. For the effective recording areaof 180° at the side of the stationary drum 129, several erasing LEDs aresemicircularly arranged in the effective recording area incorrespondence with the photodetectors 137a and 137b. The LED array 138is formed by arrangement of several LEDs.

Through the LED array 138 controls erasing circuits, it is controlledand turned on/off by the erasing control circuit 139. The photodetectors137a and 137b detect the beam emitted from the LED array 138 and controlthe corresponding erasing circuit with the detection signal.

The following is the description of the operations of this embodiment.

The erasing circuit of the erasing magnetic head E1 is in active statewhile the rotary drum 128 rotates in the direction of the arrow, thecircuit is controlled by the photodetector 137a, and the photodetector137a passes through the erasing area where the erasing LED array 138 isinstalled.

On the contrary, the erasing circuit is in non-active state while thephotodetector 137a passes through the erasing area where the LED array138 is not installed. Similarly to the erasing circuit E1, the erasingcircuit of the erasing magnetic head E2 is controlled by thephotodetector 137b.

As mentioned above, the switching signal to be directly input to theerasing circuit by the photodetectors 137a and 137b can be generatedaccording to this embodiment.

Moreover, according to this embodiment, the circuit to control theerasing circuit at the rotary drum side is very simply configured whichis able to decrease the power consumption of the circuit mounted on therotary drum. Also, at the stationary drum side, the control circuit andmechanism of the drum system can be simplified because several LEDs arearranged only for the effective recording area.

Through LEDs are used for the light emitting elements for erasingcontrol, illuminates such as EL (electroluminescence), optical fiber,and plasma display may also be used.

Through this embodiment is described by assuming that the presentinvention is applied to a rotary drum-type VTR, the invention can beapplied to the disk-type VTR which is another magnetic head mountingtype or the medium-drum-type VTR.

Also, in this embodiment, through the present invention is described asthe example to switch a 1-channel rotary transformer and a 4-channelerasing circuit by setting the magnetic-tape lap angle to 180° and a1-channel rotary transformer and a 2-channel erasing circuit or lapangle to 240°, the invention can also be applied to the example toconnect another multiple-channel erasing circuit to a 1-channel rotarytransformer with another lap angle.

In view of the recording format, or if the power consumption of anerasing circuit does not matter, the erasing circuit may constantly bebrought under active state.

In this case, it is permitted to externally control and input thecontrol signal to be supplied to erasing circuit according to the trackor range to be erased.

The following is the description of an embodiment in which a recordingmagnetic head and erasing magnetic head are mounted on a rotary drum,one or more recording circuits and one or more erasing circuits areconnected to a rotary transformer in common, and the timing to make therecording circuit(s) active is different from that to make the erasingcircuit(s) active, according to FIG. 66.

In this embodiment, the magnetic tape 142 is wound on thecircumferential surface of a rotary drum of the scanner 141 so that theeffective recording area of information signal will be 90°.

The recording circuit 143a amplifies the information signal sent fromthe rotary transformer (not illustrated) and drives the recording headR1.

The recording head R2 is installed at the position 180° apart from therecording head R1.

The recording head R2 is driven by the recording circuit 143b. Theinformation signal is recorded in the magnetic pate by the recordingheads R1 and R2.

The information signal recorded in the magnetic tape is reproduced bythe reproduction magnetic heads P1 and P2 and amplified by thereproduction circuits 144a and 144b.

The reproduction magnetic heads P1 and P2 are installed at the position180° apart from each other and the outputs of the reproduction circuits144a and 144b are connected each other and transmitted to the outside ofthe rotary drum through the rotary transformer.

Erasing is executed by the erasing circuits 145a and 145b and theerasing magnetic heads E1 and E2.

The erasing circuits 145a and 145b are connected to the recordingcircuits 143a and 143b and the rotary transformer in common. Forerasing, the erasing circuit 145a amplifies the erasing signal sent fromthe rotary transformer and drives the erasing magnetic head E1.

The erasing magnetic head E2 installed at the position 180° apart fromthe erasing magnetic head E1 is driven by the erasing circuits 145a and145b.

The following is the description of the configuration and operations ofthe erasing circuit in this embodiment according to FIGS. 67 and 68.

Information signal is recorded in a magnetic tape by the recordingmagnetic heads R1 and R2. To execute so-called insert edition in whichthe recorded information signal is erased and recorded again, erasingsignal is amplified by the rotary transformer driver circuit 146 andtransmitted to the inside of a rotary drum via the rotary transformer147.

The signal to be input to the rotary transformer driver circuit 146contains both the erasing signal of the erasing heads E1 and E2 and therecorded information signal of the recording magnetic heads R1 and R2.

The input of the recording circuits 143a and 143b and that of theerasing circuits 145a and 145b are connected to the output of the rotarytransformer 147 in common.

The recording circuits 143a and 143b and the erasing circuits 145a and145b are alternately switched to active state and non-active state bythe R1 and R2 switching signals and the E1 and E2 switching signals tobe mentioned later whenever the rotary drum rotates 90°.

Under active state, the erasing head is driven by the erasing signal andthe information signal in the magnetic tape is erased. Then, therecording head is driven by the recording circuit and new informationsignal is recorded in the data-erased magnetic tape.

The following is the description of recording and erasing circuits todecrease the number of rotary transformer channels. Because the inputsof the recording and erasing circuits are connected to a rotarytransformer in common, the input stages are configured into the emitterfollower or Darlington emitter follower type and the input impedance isset high so that frequency characteristics will not be degraded.

The following is the description of an embodiment to operate a 2-channelrecording circuit and a 1-channel erasing circuit with one rotarytransformer by setting the magnetic-tape lap angle to 120°, according toFIGS. 69 through 71.

The magnetic tape is wound around a rotary drum by 120° and data in twore-recording tracks corresponding to the recording magnetic heads R1 andR2 are simultaneously erased by the erasing magnetic head E1 previouslyto the data re-recorded information track.

That is, to execute insert edition, erasing signal is amplified by therotary transformer driver circuit 146 and transmitted to an internalcircuit of the rotary drum through the rotary transformer 147.

The signal to be input to the rotary transformer driver circuit 146contains both the erasing signal of the erasing magnetic head E1 and therecording signal of the recording magnetic heads R1 and R2.

The input of the recording circuits 143a and 143b are connected to theoutput of the rotary transformer 147 in common. The recording circuits143a and 143b and the erasing circuit 145 are alternately switched toactive state and non-active state by the R1 and R2 switching signals andthe E1 switching signal to be mentioned later whenever the rotary drumrotates 120°.

Under active state, the erasing signal is sent to the erasing magnetichead to drive the head. Thus, the information signal in the magnetictape is erased. Then the recording magnetic head is driven by therecording circuit and new information signal is recorded in thedata-erased magnetic tape.

In this embodiment, the description of the configuration of therecording and erasing circuits to decrease the number of rotarytransformer channels is omitted because the configuration is the same asthat of the embodiment in FIG. 66.

The following is the description of the method and circuit to switch arecording or erasing circuit to active state and non-active stateaccording to FIGS. 72A and 72B.

In this embodiment, the reflection-type photosensors 150a, 150b, 151a,and 151b to control recording and erasing circuits are installed on therotary drum 148 so that they will face the erasing magnetic heads E1 andE2 and the recording magnetic heads R1 and R2 respectively.

When the effective recording area of the stationary drum 149 is 90°, areflector (e.g. mirror) is installed at the recording side of therecording area and a non-reflector at the non-recording side of it.

The non-reflector is made of non-reflection material which cannot bedetected by the reflection-type photosensors.

The reflection-type photosensors 150a, 150b, 151a, and 151b have thesame configuration as that of the sensor 134a shown in FIG. 64, whichare integrated with LEDs and photodiodes (or phototransistors).

It is assumed that this embodiment uses the reflection-type photosensorto output Hi-level signals when it faces the reflector and Lo-levelsignals when it faces the non-reflector. The recording circuit is inactive state while the rotary drum 148 rotates in the direction of thearrow, the recording circuit corresponding to the recording head R1 iscontrolled by the reflection-type photosensor 151a, and the photosensor151a passes through the recording area where the reflector is installed.On the contrary, the recording circuit is in non-active state while thephotosensor 151a passes through the non-reflector.

Similarly, the recording circuit corresponding to the recording head R2is controlled by the reflection-type photosensor 151b, the erasingcircuit corresponding to the erasing head E1 by the reflection-typephotosensor 150a, and the erasing circuit corresponding to the erasinghead E2 by the reflection-type photosensor 150b.

According to this embodiment, the 90° switching signal to be directlyinput to a recording or erasing circuit can be generated by thereflection-type photosensors 150a, 150b, 151a, and 151b.

The generated signal functions as the E1, E2, R1, and R2 switchingsignals as shown in FIG. 67.

Recording and erasing in this embodiment are switched by a slip ring ora mechanical shutter installed between the reflection surface forrecording and erasing and the reflection-type photosensor.

According to this embodiment, the circuit installed on the rotary drumis simplified and the power consumption is decreased. Moreover, a glassmask having a reflection surface may be installed only in the effectiverecording area. Therefore, the cylinder-system mechanism can besimplified by using said glass mask.

The following is the description of another embodiment according toFIGS. 73A and 73B.

In this embodiment, the photodetectors 154a, 154b, 156a, and 156b tocontrol recording and erasing circuits are installed on the rotary drum148 so that they will face the magnetic heads R1 and R2, and the erasingmagnetic heads E1 and E2 respectively. In this case, the recording headsR1 and R2 are installed at the position 180° apart from each other.Similarly, the erasing magnetic heads E1 and E2 are installed at theposition 180° apart from each other.

When the effective recording area of the stationary drum 149 is 90°,several recording and erasing LEDs are installed in the effectiverecording area so that they will face the photodetectors 154a, 154b,156a, and 156b.

The recording circuit is controlled by the recording LED array 158installed on the stationary drum and the erasing circuit by the erasingLED array 155. That is, when the photodetectors 154a, 154b, 156a, and156b receive the beam emitted from the recording LED array 158 and theerasing LED array 155, the recording and erasing circuits are controlledby the detection signal of these photodetectors.

The following is the description of the 90° switching circuit of thisembodiment.

The R1 recording circuit is in active state while the rotary drumrotates in the direction of the arrow, the R1 recording circuit iscontrolled by the photodetector 156a, and the photodetector 156a passesover the recording area where the recording LED array 158 is installed.

On the contrary, the recording circuit is in non-active state while thephotodetector passes over the area where the recording LED array 158 isnot installed.

Similarly, the R2 recording circuit is controlled by the photodetector156b and the E1 erasing circuit by the photodetector 154a.

While the photodetector 154a passes over the recording area where theerasing LED array 155 is installed, the E1 erasing circuit is in activestate.

On the contrary, while the photodetector passes over the area where theerasing LED array 155 is not installed, the E1 erasing circuit is innon-active state. Similarly, the E2 erasing circuit is controlled by thephotodetector 154b.

According to this embodiment, the 90° switching signal to be directlyinput to a recording or erasing circuit can be generated.

The generated signal contains the E1, E2, R1, and R2 switching signalsas shown in FIG. 67.

The invention related to the above embodiment can also be applied toswitching of a multiple-channel recording circuit or erasing circuit ora multiple-channel recording/erasing circuit. For example, if thepresent invention is applied to an apparatus in which a 4-channelrecording head and recording circuit and a 4-chanel erasing head anderasing circuit are used and the effective recording area angle is 45°,switching can be executed by a 1-channel rotary transformer.

Also, the present invention can be applied to a so-called self-recordinghead which performs recording and reproduction with one head.

Moreover, the present invention allows a recording circuit and erasingcircuit to be respectively integrated or both circuits to be combinedand integrated. It also allows several circuit windings corresponding tothe number of recording and erasing circuits to be arranged in onewinding slot of a rotary transformer.

The following is the description of an embodiment in which areproduction magnetic head and erasing magnetic head are mounted on arotary drum together, one or more reproduction circuits and one or moreerasing circuits are connected to a 1-channel rotary transform incommon, and the timing to drive the reproduction circuit is differentfrom that to drive the erasing circuit, according to FIGS. 74 through76.

In this embodiment, the magnetic tape 162 is wound on thecircumferential surface of the rotary drum of the scanner 161 so thatthe effective recording area of information signal will be 180°.

The recording circuit 163a amplifies the information signal sent fromthe rotary transformer (not illustrated) and drives the recording headR1.

The recording head R2 is installed at the position 180° apart from therecording head R1.

The recording head R2 is driven by the recording circuit 163b. Theinformation signal is recorded in the magnetic tape by the recordingheads R1 and R2.

The information signal recorded in the magnetic tape is reproduced bythe reproduction magnetic heads P1 and P2 and amplified by thereproduction circuits 164a and 164b.

The reproduction magnetic heads P1 and P2 are installed at the position180° apart from each other and the outputs of the reproduction circuits164a and 164b are connected each other and transmitted to the outside ofthe rotary drum through the rotary transformer.

Erasing is executed by the erasing circuits 165a and 165b and theerasing magnetic heads E1 and E2.

The erasing circuits 165a and 165b are connected to the recordingcircuits 163a and 163b and the rotary transformer in common. Forerasing, the erasing circuit 165a amplifies the erasing signal sent fromthe rotary transformer and drives the erasing magnetic head E1.

The erasing magnetic head E2 installed at the position 180° apart fromthe erasing magnetic head E1 is driven by the erasing circuits 165a and165b.

As shown in FIGS. 75 and 76, information signals are recorded in themagnetic tape by the recording magnetic heads R1 and R2. However, toexecute so-called insert edition to erase the recorded informationsignal and record it again, the erasing signal is amplified by therotary transformer driver circuit 166 and transmitted to the inside ofthe rotary drum through the rotary transformer 167. The rotarytransformer driver circuit 166 is connected to the rotary transformerreceiver circuit 168 and the rotary transformer 167.

For rotary erasing, because the erasing/reproduction switching signalgoes to Lo level, the rotary transformer receiver circuit 168 goes to anon-active state and the erasing rotary transformer drive 166 to anactive state.

The erasing circuits 165a and 165b are alternately switched to theactive state and non-active state by the E1 and E2 switching signalsevery 180° of rotation to drive the erasing magnetic heads E1 and E2 byapplying erasing current to these heads under the active state.

Thus, the information signal in the magnetic tape 162 is erased by theerasing magnetic head. In this case, the reproduction circuits 164a and164b turn off both the P1 and P2 switching signals.

The new information signal input to the recording circuit transformerdrive 169 is amplified and transmitted to an internal circuit of therotary drum through the recording circuit transformer 170.

The recording rotary transformer 170 and recording circuits 163a and163b are connected together and the recording circuits 163a and 163b areswitched to active state and non-active state by the R1 and R2 switchingsignal every 180° of rotation.

In the active state, the recording circuits 163a and 163b drive therecording magnetic heads R1 and R2 to record the information signal inthe data-erased magnetic tape.

After the above insert edition, because the E1 and E2 switching signalsare turned off, rotary erasing and erasing signal input are stopped.

Then, the erasing/reproduction switching signal is set to Hi level andthe erasing rotary transformer driver circuit 166 and rotary transformerreceiver circuit 168 go to the non-active state. Then, the P1 and P2switching signals are sequentially turned on according to the rotationof the rotary drum.

Thus, the information signals sent from the reproduction magnetic headsP1 and P2 are amplified by the reproduction circuits 164a and 164b andtransmitted to the outside of the rotary drum through the rotarytransformer 167.

The transmitted information signal is amplified by the rotarytransformer receiver circuit 168 again.

When normal recording is executed while erasing is executed by astationary head, as shown in FIG. 76; the erasing/reproduction switchingsignal is set to Hi level, the erasing rotary transformer driver circuit166 goes to the non-active state, and the rotary transformer receivercircuit 168 goes to the active state.

In this case, the information signal to be recorded is transmittedthrough route previously mentioned and input to the recording circuits163a and 163b.

The recording circuits 163a and 163b drive the recording magnetic headsR1 and R2 according to information signal to record the informationsignal in a magnetic tape.

The recorded information signal is immediately reproduced by thereproduction magnetic heads P1 and P2 (simultaneous reproduction).

The information signal reproduced by the reproduction magnetic heads P1and P2 is amplified by the reproduction circuits 164a and 164b andtransmitted through the route previously mentioned. In this embodiment,the method to decrease the number of rotary transformer channels usesthe same configuration as that in the previous embodiment.

The rotary transformer receiver 168 connected to the rotary transformerin common can be switched to the erasing rotary transformer drivercircuit 166 to be mentioned later by the same means as erasing circuit.

Because the reproduction circuit is connected to the input of theerasing circuit and the rotary transformer in common, the output of thereproduction circuit under non-active state goest to a high impedancestate so that frequency characteristics of the erasing circuit underactive state will not be degraded. Therefore, the circuit to bring theoutput of the reproduction circuit shown in FIG. 4 into high impedanceis installed. The description of the method and circuit (180° switchingcircuit) to alternately switch a reproduction circuit or erasing circuitto active state and non-active state in this embodiment is omittedbecause the method and circuit are the same as those of the embodimentshown in FIGS. 60A through 65B.

The following is the description of recording/reproduction apparatusesaccording to various specifications.

First, description is made on a recording apparatus using severalrecording-only magnetic heads and a one-winding rotary transformeraccording to FIG. 77.

In the recording apparatus in FIG. 77, inputs of the recording heads R1through Rh are connected to outputs of the recording circuits REC1through RECk respectively.

The inputs of the recording circuits REC1 through RECk are connected incommon and connected to the secondary winding of the rotary transformerTR.

The primary winding of the rotary transformer TR is connected to theoutput of the rotary-transformer driver circuit DR.

The following is the description of the arrangement of recording headsof the recording apparatus using said recording circuits at various tapelap angles and the transmission state of the recording signal to beinput to said recording heads from the rotary transformer.

In the lap angle is set to 180° as shown in FIG. 78A, two recordingmagnetic heads R1 and R2 are installed on a rotary drum so that theywill be faced to each other at the interval of 180°. In this embodiment,the rotary transformer TR sends recording signal to the recordingmagnetic heads R1 and R2 alternately as shown in FIG. 78B.

According to the recording apparatus with the above configuration, thenumber of rotary transformers can be decreased to 1/2 the number ofrecording magnetic heads and recording circuits.

Moreover, the number of rotary transformer driver circuits can bedecreased to 1/2 the number of recording magnetic heads and recordingcircuits. Thus, power consumption can be decreased. If the lap angle isset to 120° as shown in FIG. 79A, three recording magnetic heads R1, R2,and R3 are installed on the rotary drum at the interval of 120°.

In this embodiment, the rotary transformer TR repeatedly sends recordingsignal to the recording magnetic heads R1, R2, and R3 in order as shownin FIG. 79B.

According to the recording apparatus with the above configuration, thenumber of rotary transformers can be decreased to 1/3 the number ofrecording magnetic heads and recording circuits. Moreover, the number ofrotary transformer driver circuits can be decreased to 1/3 the number ofrecording magnetic heads and recording circuits.

Therefore, power consumption can be decreased.

If the lap angle is set to (360/H)° as shown in FIG. 80A, 360/Hrecording magnetic heads R1, R2, . . . , and RH are installed on therotary drum at the interval of (360/H)°.

In this embodiment, the rotary transformer TR repeatedly sends thecorresponding recording signal to the recording magnetic heads R1, R2, .. . , and RH in order.

According to the recording apparatus with the above configuration, therecording signals of the magnetic head R1 and R1 recording circuit (notshown) through the magnetic head RH and the K recording circuit (notshown) can be transmitted by the rotary transformer TR.

Therefore, the number of rotary transformers can be decreased to 1/H thenumber of recording magnetic heads and recording circuits. Moreover, thenumber of rotary transformer driver circuits can be decreased to 1/H thenumber of recording magnetic heads and recording circuits.

If the lap angle is set to 90° as shown in FIG. 81A, four recordingmagnetic heads R1 through R4 are installed on the rotary transformer atthe interval of 90°. In this embodiment, the rotary transformer TRrepeatedly sends the corresponding recording signal to the recordingmagnetic heads R1 through R4 in order.

According to the apparatus with the above configuration, the number ofrotary transformers can be deceased to 1/4 the number of recordingmagnetic heads and recording circuits. Moreover, the number of rotarytransformer driver circuits can be decreased to 1/4 the number ofrecording magnetic heads and recording circuits. Therefore, powerconsumption can be decreased. In the recording apparatus shown in FIG.82A, two sets of magnetic heads R1 and R2 and R1' and R2' are installedand the magnetic heads of each set are installed with the lap angle of180°.

That is, the first set of recording magnetic heads R1 and R2 and thesecond set of recording magnetic heads R1' and R2' are installed on therotary transformer at the interval of 180° respectively, and two sets ofrecording magnetic heads are perpendicularly arranged.

In this embodiment, the first set of magnetic heads R1 and R2 and thesecond set of magnetic heads R1' and R2' receive recording signal fromanother rotary transformer TR. That is, recording signal is repeatedlysupplied to the first set of magnetic heads in order of R1, R2, R1, andR2 from the rotary transformer as shown in FIG. 82B. Similarly,recording signal is repeatedly supplied to the second set of magneticheads R1' and R2' from another rotary transformer in order of R1', R2',R1', and R2'. According to the apparatus with the above configuration,the number of rotary transformers can be decreased to 1/2 the number ofrecording magnetic heads and recording circuits. Moreover, the number ofrotary transformer driver circuits can be decreased to 1/2 the number ofrecording magnetic heads and recording circuits. Therefore, powerconsumption can be deceased.

In the recording apparatus shown in FIG. 83A, two pairs of magneticheads R1 and R2 and R1' and R2' are installed and magnetic heads of eachset are arranged with the lap angle of 180°. That is, the first pair ofrecording magnetic heads R1 and R2 and the second pair of magnetic headsR1' and R2' are installed on the rotary drum at the interval of 180°respectively. In this case, two pairs of the magnetic heads may not beperpendicular to each other and the height of each magnetic head is setso that it will meet the recording format of magnetic tape.

In this embodiment, the first pair of magnetic heads R1 and R2 and thesecond pair of magnetic heads R1' and R2' receive recording signal fromanother rotary transformer TR. That is, recording signal is repeatedlysupplied to the first pair of magnetic heads from the rotary transformerin order of R1, R2, R1, and R2 as shown in FIG. 83B. Similarly,recording signal is repeatedly supplied to the second pair of magneticheads R1' and R2' from another rotary transformer in order of R1', R2',R2', and R2'. According to the recording apparatus with the aboveconfiguration, the number of rotary transformer is can be decreased to1/2 the number of recording magnetic heads and recording circuits.Moreover, the number of rotary transformer driver circuits can bedecreased to 1/2 the number of recording magnetic heads and recordingcircuits. Therefore, power consumption can be decreased.

In this recording apparatus in FIG. 84, the rotary transformer TR isused in which several secondary windings are set in one winding slot.These secondary windings of the rotary transformer TR are connected tothe inputs of the recording circuits REC1 through RECk respectively. Theoutputs of the recording circuits REC1 through RECk are connected to theinputs of the recording magnetic heads R1 through RH respectively. Theprimary winding of the rotary transformer TR is connected to the outputof the rotary transformer driver circuit DR.

This type of circuit can be applied to the magnetic heads shown in FIGS.78A through 83A.

According to the apparatus with the above configuration, because thewinding leading terminal of a rotary transformer can be installed at theposition close to each recording circuit, the substrate pattern issimplified and the wire length is decreased. Thus, frequencycharacteristics are improved. Moreover, the effect same as that of theapparatus in FIG. 77 can be obtained. FIG. 85 shows a circuit of areproduction apparatus. In this circuit, the outputs of the reproductionmagnetic heads P1 through PH are connected to the outputs of thereproduction circuits PLAY1 through PLAYk respectively. The inputs ofthe reproduction circuits PLAY1 through PLAYk are connected in commonand connected to the primary winding of the rotary transformer TR.

The secondary winding of the rotary transformer TR is connected to theinput of the rotary transformer receiver circuit DE. The following isthe description of the arrangement of the reproduction heads of thereproduction apparatus using said reproduction circuits at various tapelap angles and the transmission state of the recording signal to beinput to the recording heads from a rotary transformer.

If the lap angle is set to 180° as shown in FIG. 86A, two reproductionmagnetic heads P1 and P2 are installed on a rotary drum so that theywill face each other at the interval of 180°.

In this embodiment, the rotary transformer TR receives reproductionsignal alternately from the reproduction magnetic heads P1 and P2 asshown in FIG. 86B.

According to the reproduction apparatus with the above configuration,the number of rotary transformers can be decreased to 1/2 the number ofreproduction magnetic heads and reproduction circuits. Moreover, thenumber of rotary transformer receiver circuits can be decreased to 1/2the number of reproduction magnetic heads and reproduction circuits.Therefore, power consumption can be decreased.

If the lap angle is set to 120° as shown in FIG. 87A, three reproductionmagnetic heads P1, P2, and P3 are installed on a rotary drum at theinterval of 120°. In this embodiment, reproduction signal is repeatedlysupplied to the rotary transformer TR from the reproduction magneticheads P1, P2, and P3 in order as shown in FIG. 87B.

According to the reproduction apparatus with the above configuration,the number of rotary transformers can be decreased to 1/3 the number ofreproduction magnetic heads and reproduction circuits. Moreover, thenumber of rotary transformer receiver circuits can be decreased to 1/3the number of reproduction magnetic heads and reproduction circuits.Therefore, power consumption can be decreased.

If the lap angle is set to (360/H)° as shown in FIG. 88A, 360/Hreproduction magnetic heads P1, P2, . . . , and PH are installed on arotary drum at the interval of (360/H)°. In this embodiment,reproduction signal is repeatedly supplied to the rotary transformer TRfrom the reproduction magnetic heads P1, P2, . . . , and PH in order asshown in FIG. 88B.

According to the reproduction apparatus with the above configuration,the reproduction signals of the magnetic head P1 and the P1 recordingcircuit (not shown) through the magnetic head PH and the S reproductioncircuit (not shown) can be transmitted by one rotary transformer TR.

Therefore, the number of rotary transformers can be decreased to 1/H thenumber of reproduction magnetic heads and reproduction circuits.Moreover, the number of rotary transformer receiver circuits can bedecreased to 1/H the number of reproduction magnetic heads andreproduction circuits. Therefore, power consumption can be decreased.

If the lap angle is set to 45° as shown in FIG. 89A, eight reproductionmagnetic heads P1 through P8 installed on a rotary drum at the intervalof 45°. In this embodiment, reproduction signal is repeatedly suppliedto the rotary transformer TR from the reproduction magnetic heads P1through P8 in order as shown in FIG. 89B.

According to the recording apparatus with the above configuration, thenumber of rotary transformers can be decreased to 1/8 the number ofreproduction magnetic heads and reproduction circuits. Moreover, thenumber of rotary transformer receiver circuits can be decreased to 1/8the number of reproduction magnetic heads and reproduction circuits.Therefore, power consumption can be decreased.

In the reproduction apparatus shown in FIG. 90A, four sets of magneticheads P1 through P5, P2 and P6, P3 and P7, and P4 and P8 are installedand the magnetic heads of each set are arranged with the lap angle of180°.

These sets of magnetic heads are sequentially arranged at the angle of45°.

In this embodiment, the reproduction signal from each set of magneticheads is supplied to each corresponding rotary transformer. For example,as shown in FIG. 90B, reproduction signals is repeatedly supplied to therotary transformer from the reproduction magnetic heads P1 and P5 inorder.

Similarly, reproduction signal is repeatedly supplied to another rotarytransformer from the second set of reproduction heads P2 and P6 inorder.

According to the reproduction apparatus with the above configuration,the number of rotary transformers can be decreased to 1/2 the number ofreproduction magnetic heads and reproduction circuits. Moreover, thenumber of rotary transformer receiver circuits can be decreased to 1/2the number of reproduction magnetic heads and reproduction circuits.Therefore, power consumption can be decreased.

In the reproduction apparatus shown in FIG. 91A, two pairs of magneticheads P1 and P2 and P1' and P2' are installed and magnetic heads of eachpair are arranged with the lap angle of 180°. That is, the first pair ofreproduction magnetic heads P1 and P2 and the second pair of magneticheads P1' and P2' are installed on a rotary drum at the interval of 180°respectively. In this case, two pairs of the magnetic heads may not beperpendicular to each other, and the height of each magnetic head is setso that it will meet the recording format of the magnetic tape.

In this embodiment, the first pair of magnetic heads P1 and P2 and thesecond pair of magnetic heads P1' and P2' supply reproduction signal toanother rotary transformer TR. That is, reproduction signal isrepeatedly supplied to the first pair of magnetic heads of the rotarytransformer from the reproduction magnetic heads P1, P2, P1, and P2 inorder as shown in FIG. 91B.

Similarly, reproduction signal is repeatedly supplied to the second pairof magnetic heads P1' and P2' of another rotary transformer in order ofP1', P2', P1', and P2'.

According to the reproduction apparatus with the above configuration,the number of rotary transformers can be decreased to 1/2 the number ofreproduction magnetic heads and reproduction circuits. Moreover, thenumber of rotary transformer receiver circuits can be decreased to 1/2the number of reproduction magnetic heads and reproduction circuits.Therefore, power consumption can be decreased.

The reproduction apparatus in FIG. 92 uses the rotary transformer TRwith several secondary windings set in one winding slot. These secondarywindings of the rotary transformer TR are connected to the outputs ofthe reproduction circuits PLAY1 through PLAYk respectively. The inputsof these reproduction circuits PLAY1 through PLAYk are connected to theoutputs of the reproduction magnetic heads P1 through PH respectively.

The primary winding of the rotary transformer TR is connected to theinput of the rotary transformer receiver circuit RE. These circuits canbe applied to the magnetic heads shown in FIGS. 86A through 91A.

According to the reproduction apparatus with the above configuration,the substrate pattern is simplified and the wire length is decreasedbecause the leading terminal of the rotary transformer winding can beinstalled at the position close to each reproduction circuit. Therefore,frequency characteristics are improved. Moreover, the same effect asthat of the apparatus in FIG. 85 can be obtained.

FIG. 93 shows a magnetic recording/reproduction apparatus.

The magnetic recording/reproduction apparatus is made by combining therecording apparatus in FIG. 77 and the reproduction apparatus in FIG.85. That is, the recording apparatus comprises the recording magneticheads R1 through Rh, the recording circuits REC1 through RECk which areconnected to the inputs of said magnetic heads respectively, the inputsof said recording circuits REC1 through RECk, the rotary transformerdriver circuit DR, and the rotary transformer RTR connected between therecording circuits and the rotary transformer driver.

The reproduction apparatus comprises the reproduction magnetic heads P1through PH, the reproduction circuits PLAY1 through PLAYk which areconnected to the outputs of said reproduction magnetic headsrespectively, the rotary transformer receiver circuit DE, and the rotarytransformer PTR connected between the reproduction circuits PLAY1through PLAYk and the rotary transformer receiver.

In the above configuration, the height and position of each recordingmagnetic head and those of the corresponding reproduction magnetic headare determined according to the recording format of the magnetic tape sothat the data in the track recorded by each recording magnetic head willbe reproduced by the corresponding reproduction magnetic head.

In this case, the angle of the reproduction head corresponding to arecording head can optionally be set.

If the tape lap angle is set to 180°, the recording magnetic heads R1and R2 are installed so that they will face each other at the intervalof 180° as shown in FIG. 94A and also the reproduction magnetic heads P1and P2 are installed so that they will face each other at the intervalof 180°.

In this case, as shown in FIG. 94B, recording signal is repeatedlytransmitted to the recording magnetic heads R1 and R2 in order throughone recording rotary transformer RTR and the reproduction signal sentfrom the reproduction magnetic heads P1 and P2 is repeatedly transmittedin order of P1, P2, P1, and P2 through one reproduction rotarytransformer.

According to the reproduction apparatus with the above configuration,the number of rotary transformers can be decreases to 1/2 the number ofmagnetic heads and recording (reproduction) circuits in both therecording and reproduction systems. Also, the number of rotarytransformer drivers and that of rotary transformer receivers can bedecreases to 1/2 the number of them.

The recording/reproduction apparatus in FIG. 94A is able to readrecorded information twice or three times by increasing the number ofreproduction magnetic heads. Therefore, the frequency of data error canbe decreased. If precedent reproduction heads are added, re-recording isrealized after precedent reproduction. If the tape lap angle is set to180°, the sets of reproduction magnetic heads P1 and P4, P2 and P5, P3and P6, . . . can be installed for a set of recording magnetic heads R1and R2 as shown in FIG. 95A.

In this case, as shown in FIG. 95B, the information signal recorded bythe recording magnetic heads R1 and R2 in order is reproduced by thereproduction magnetic heads P2 and P5 in the same order. For specialreproduction the information signal recorded by the recording magneticheads R1 and R2 is repeatedly reproduced by the reproduction magneticheads P1 through P6 in order.

Also said recording/reproduction apparatus decreases the number ofrotary transformer to 1/2 the number of magnetic heads and recording(reproduction) circuits and the number of rotary transformer receiversand that of magnetic heads to the number of magnetic heads and recording(reproduction) circuits.

This embodiment is also able to read recorded information twice or threetimes by increasing the number of reproduction magnetic heads.

Thus, the frequency of data error can be decreased.

If the magnetic heads P3 and P6 are used as precedent reproductionheads, re-recording is realized by the recording magnetic heads R1 andR2 after precedent reproduction.

FIG. 96A shown a recording/reproduction apparatus made by combining therecording apparatus in FIG. 84 and the reproduction apparatus in FIG.92. This recording/reproduction apparatus uses rotary transformers RTRand PTR with several secondary windings set in one slot respectively.

In this case, several recording systems (including recording heads andrecording circuits) and several reproduction systems (includingreproduction heads and reproduction circuits) are alternately installed.

The secondary windings of the rotary transformer RTR are connected torecording circuits REC1 through RECk respectively and the outputs of therecording circuits REC1 through RECk to the inputs of the recordingmagnetic heads R1 through RH respectively.

The primary winding of the rotary transformer TR is connected to theoutput of the rotary transformer driver circuit DR.

Similarly, the secondary windings of the rotary transformer PTR areconnected to the outputs of the reproduction circuits PLAY1 throughPLAYk respectively, and the inputs of the reproduction circuits PLAY1through PLAYk to the outputs of the reproduction magnetic heads P1through PH respectively. The primary winding of the rotary transformerPTR is connected to the input of the rotary transformer receiver circuitRE.

FIG. 96B shows a rotary drum containing the recording and reproductionmagnetic heads in FIG. 96A.

In this embodiment, like the previous embodiment, the tape lap angle isset to 180° and the height and position of each recording magnetic headand those of the corresponding reproduction magnetic head are determinedaccording to the recording format of the magnetic tape so that data inthe track recorded by each recording magnetic head will be reproduced bythe corresponding reproduction magnetic head. The angle of thereproduction head corresponding to a recording head can optionally beset.

For this embodiment, the recording magnetic heads R1 through R16 and thereproduction magnetic heads P1 through P16 are alternately installed inthe circumferential direction and every two magnetic heads are faced toeach other.

In the above recording/reproduction apparatus, recorded informationsignal is input to the recording magnetic head R1 and the R1 recordingcircuit and the recording magnetic head R9 and the R9 recording circuitfrom one rotary transformer. The reproduction magnetic head P1 and theP1 reproduction circuit, and the reproduction magnetic head P1 and theP1 reproduction circuit send reproduction signal to one rotarytransformer.

Similarly, each set of the recording magnetic heads R2 and R10, R3 andR11, R4 and R12, R5 and R13, R6 and R14, R7 and R15, and R8 and R16receives recorded information signal from one rotary transformer.

Each set of the reproduction magnetic heads P2 and P10, P3 and P11, P4and P12, P5 and P13, P6 and P14, P7 and P15, and P8 and P16 sendsreproduction information signal to one rotary transformer.

Therefore, this embodiment requires a rotary transformer equivalent to16 channels.

According to this embodiment, like the previous embodiment, the numberof rotary transformers can be decreased to 1/2 the number of recordingmagnetic heads and spare recording circuits and also to 1/2 the numberof reproduction magnetic heads and reproduction circuits. Moreover, thenumber of rotary transformer driver circuits can be decreased to 1/2 thenumber of recording magnetic heads and recording circuits and the numberof rotary transformer receiver circuits to 1/2 the number ofreproduction magnetic heads and reproduction circuits.

Also in this embodiment, because the leading terminal of rotarytransformers can be installed at the position close to each reproductioncircuit, the substrate pattern is simplified and the wire length isdecreased.

Thus, frequency characteristics are improved. Moreover, recordedinformation can be read twice or three times by increasing the number ofreproduction magnetic heads.

Therefore, the frequency of data error can be decreased. If precedentreproduction heads are added, re-recording is realized after precedentreproduction.

The following is the description of various modified embodiments of arecording/reproduction apparatus using magnetic heads dedicated torecording and those dedicated to reproduction according to FIGS. 97through 106.

In the modified embodiment in FIG. 97, several recording circuits (REC)and several reproduction circuits (PLAY) are connected to the rotarytransformer driver circuit DR and rotary transformer receiver circuit REthrough one rotary transformer TR.

In the modified embodiment in FIG. 98; one rotary transformer having oneprimary winding and two secondary windings are installed, and the rotarytransformer driver circuit DR and rotary transformer receiver circuit REare connected to the primary winding, several recording circuits (REC)to one secondary winding, and several reproduction circuits (PLAY) tothe other secondary winding.

In the modified embodiment in FIG. 99, the rotary transformer TR hasseveral secondary windings connected to several recording circuits andseveral reproduction circuits respectively and a primary windingconnected to one rotary transformer driver circuit DR and one rotarytransformer receiver circuit RE in common.

In the modified embodiment in FIG. 100, the rotary transformer TR hastwo primary windings connected to the rotary transformer driver circuitDR and rotary transformer receiver circuit RE respectively and asecondary winding connected to several recording circuits and severalreproduction circuits in common.

In the modified embodiment in FIG. 101, the rotary transformer TR hastwo primary windings and two secondary windings, and said primarywindings are connected to a rotary transformer driver circuit and rotarytransformer receiver circuit respectively, one secondary winding toseveral recording circuits in common, and the other secondary winding toseveral reproduction circuits in common.

In the modified embodiment in FIG. 102, the rotary transformer TR hasseveral secondary windings connected to several recording circuits andseveral reproduction circuits respectively and two primary windingsconnected to one rotary transformer driver circuit DR and one rotarytransformer receiver circuit RE respectively.

In the modified embodiment in FIG. 103, several rotary transformers areinstalled, and recording circuits and reproduction circuits areconnected to the primary winding of each rotary transformer in commonand one rotary transformer driver circuit and one rotary transformerreceiver circuit are connected to secondary windings in common.

According this embodiment, the signal recorded by a recording magnetichead can immediately be reproduced by a reproduction head.

In the modified embodiment in FIG. 104, several rotary transformers areinstalled each of which has one primary winding and two secondarywindings. In this embodiment, recording and reproduction circuits areconnected to two secondary windings of each rotary transformer and onerotary transformer driver circuit and one rotary transformer receivercircuit are connected to one primary winding in common.

In the modified embodiment in FIG. 105, several rotary transformers areinstalled each of which has two primary winding and one secondarywinding. In this embodiment, one rotary transformer driver circuit andone rotary transformer receiver circuit are connected to two primarywindings of each rotary transformer, and recording and reproductioncircuits are connected to one secondary winding in common.

In the modified embodiment in FIG. 106, several rotary transformers areinstalled each of which has two primary windings and two secondarywindings. In this embodiment, one rotary transformer driver circuit andone rotary transformer receiver circuit are connected to two primarywindings of each rotary transformer, and recording and reproductioncircuits are connected to two secondary windings respectively.

The following is the description of various modified embodiments of arecording/reproduction apparatus using magnetic heads for both recordingand reproduction according to FIGS. 107 through 118.

In the modified embodiment in FIG. 107, severalrecording-and-reproduction magnetic heads and several rotarytransformers are installed. Each recording-and-reproduction magnetichead is connected to the secondary windings of two rotary transformers,and one rotary transformer driver circuit and one rotary transformerreceiver circuit are connected to each primary winding of these rotarytransformers.

In the modified embodiment in FIG. 108, two recording-and-reproductionmagnetic heads and two rotary transformers are installed. Each rotarytransformer has two secondary windings and one primary winding. Onerecording-and-reproduction magnetic head is connected to one secondarywinding of two rotary transformers respectively through recording andreproduction circuits and the other recording-and-reproduction magnetichead to the other secondary winding of two rotary transformersrespectively through recording and reproduction circuits. One rotarytransformer driver circuit and one rotary transformer receiver circuitare connected to the primary windings of these rotary transformersrespectively.

In the modified embodiment in FIG. 109, severalrecording-and-reproduction magnetic heads and one rotary transformer areinstalled. Each recording-and-reproduction magnetic head is connected tothe secondary winding of the rotary transformer through recording andreproduction circuits in common, and one rotary transformer drivercircuit and one rotary transformer receiver circuit are connected to theprimary winding of the rotary transformer in common.

In the modified embodiment in FIG. 110, severalrecording-and-reproduction magnetic heads and one rotary transformerhaving one primary winding and two secondary windings are installed.Each recording-and-reproduction magnetic head is connected to twosecondary windings of the rotary transformer respectively through thecorresponding recording circuit and reproduction circuit, and one rotarytransformer receiver circuit are connected to the primary winding of therotary transformer in common.

In the modified embodiment in FIG. 111, severalrecording-and-reproduction magnetic heads and one rotary transformerhaving one primary winding and several secondary windings are installed.Each recording-and-reproduction magnetic head is connected to thesecondary winding of the rotary transformer through the correspondingrecording circuit and reproduction circuit, and one rotary transformerdriver circuit and one rotary transformer receiver circuit are connectedto the primary winding of the rotary transformer in common.

In the modified embodiment in FIG. 112, severalrecording-and-reproduction magnetic heads and one rotary transformerhaving two primary windings and one secondary winding are installed.

Each recording-and-reproduction magnetic head is connected to thesecondary winding of the rotary transformer in common through thecorresponding recording circuit and reproduction circuit, and one rotarytransformer driver circuit and one rotary transformer receiver circuitare connected to the two primary windings of the rotary transformerrespectively through the corresponding recording circuit andreproduction circuit.

In the modified embodiment in FIG. 113, severalrecording-and-reproduction magnetic heads and one rotary transformerhaving two primary winding and two secondary windings are installed.Each recording-and-reproduction magnetic head is connected to the twosecondary windings respectively through the corresponding recordingcircuit and reproduction circuit, and one rotary transformer drivercircuit and one rotary transformer receiver circuit are connected to thetwo primary windings of the rotary transformer respectively.

In the modified embodiment in FIG. 114, severalrecording-and-reproduction magnetic heads and one rotary transformerhaving two primary windings and several secondary windings areinstalled. Each recording-and-reproduction magnetic head is connected tothe secondary windings of the rotary transformer respectively throughthe corresponding recording circuit and reproduction circuit, and onerotary transformer driver circuit and one rotary transformer receivercircuit are connected to the two primary windings of the rotarytransformer respectively.

In the modified embodiment in FIG. 115, severalrecording-and-reproduction magnetic heads and several rotarytransformers each of which has one primary winding and one secondarywinding are installed. Each recording-and-reproduction magnetic head isconnected to the secondary winding of the corresponding rotarytransformer through the corresponding recording circuit and reproductioncircuit in parallel, and the corresponding rotary transformer drivercircuit and rotary transformer receiver circuit are connected to theprimary winding of the rotary transformer in common.

In the modified embodiment in FIG. 116, severalrecording-and-reproduction magnetic heads and several rotarytransformers each of which has one primary winding and two secondarywindings are installed. Each recording-and-reproduction magnetic head isconnected to the secondary windings of the corresponding rotarytransformer through the corresponding recording circuit and reproductioncircuit, and the corresponding rotary transformer driver circuit androtary transformer receiver circuit are connected to the primary windingof the rotary transformer in common.

In the modified embodiment in FIG. 117, severalrecording-and-reproduction magnetic heads and several rotarytransformers each of which has two primary windings and one secondarywinding are installed. each recording-and-reproduction magnetic head isconnected to the secondary winding of the corresponding rotarytransformer through the corresponding recording circuit and reproductioncircuit in parallel, and the corresponding rotary transformer drivercircuit and rotary transformer receiver circuit are connected to theprimary windings of the rotary transformer respectively.

In the modified embodiment in FIG. 118, severalrecording-and-reproduction magnetic heads and several rotarytransformers each of which has tow primary windings and two secondarywindings are installed. Each recording-and-reproduction magnetic head isconnected to the secondary windings of the corresponding rotarytransformer through the corresponding recording circuit and reproductioncircuit, and the corresponding rotary transformer driver circuit androtary transformer receiver circuit are connected to the primarywindings of the rotary transformer respectively.

The embodiments of FIGS. 2, 5A, 5B, 7, 55, 58, 67, 70, and 75 use amagnetic recording/reproduction circuit which has a primary winding anda secondary winding wound in each winding slot in the rotor and statorof each of the rotary transformers 6a and 6b. In contrast, FIGS. 119through 126 show embodiments in which a plurality of winding coils arewound around an axis of rotation of the rotor in a winding slot in therotor or stator of the rotary transformer.

Specifically, in the recording/reproduction circuit of FIG. 119, whichcorresponds to the recording/reproduction circuit of FIG. 2, a primarywinding, e.g. a single coil PW is wound and housed in a winding slot inthe stator of the rotary transformer 6a, and two secondary windings,e.g. two coils SW1 and SW2 are wound and housed in one winding slot inits rotor, whereas two primary windings, e.g. two coils PW1 and PW2 arewound and housed in a winding slot in the rotor of the rotarytransformer 6b, and a secondary winding SW is wound and housed in awinding slot in its stator. Each of the coils is wound around an axis ofrotation of the rotor of the rotary transformer. A resistor R of 50 to1,000 Ω for example, preferable 150 Ω is connected across two terminalsof each of the coils PW1 and PW2 connected to the recording amplifiers3a and 3b, respectively.

The construction of a transformer core that has two windings in awinding slot is shown in FIG. 18. The recording circuit in this figureis equivalent to the schematic circuit of FIG. 19, and the reproductioncircuit is equivalent to the schematic circuit of FIG. 21.

The recording circuit and reproduction circuit shown in FIG. 120A and120B correspond to the embodiments in FIGS. 5A and 5b, respectively.FIG. 120A shows a recording circuit using a rotary transformer in whicha primary winding, e.g. a single coil is wound and housed in a windingslot in the stator of the rotary transformer of each channel in therotary transformer 105, and two secondary windings, e.g. two coils arewound and housed in a winding slot in its rotor. FIG. 120B shows areproduction circuit using a rotary transformer in which a secondarywinding, e.g. a single coil is wound and housed in a winding slot in thestator of the rotary transformer of each channel in the rotarytransformer 120, and two primary windings, e.g. two coils are wound andhoused in a winding slot in its rotor. Each of the coils is wound aroundan axis of rotation of the rotor of the rotary transformer.

The recording/reproduction circuit in FIG. 121 corresponds to therecording/reproduction circuit of FIG. 7. The recording/reproductioncircuit of FIG. 121 uses a rotary transformer in which a winding (asingle coil) connected to both of an input amplifier 5a and an outputamplifier 7a is wound and housed in a winding slot in the stator of therotary transformer 6a, and two windings (two coils) connected to arecord signal amplifier 3a and a reproduction signal amplifier 4a,respectively, are wound and housed in a winding slot in its rotor,whereas a winding (a single coil) connected to both of an inputamplifier 5b and an output amplifier 7b is wound and housed in a windingslot in the stator of the rotary transformer 6b, and two windings (twocoils) connected to a record signal amplifier 3b and a reproductionsignal amplifier 4b, respectively, are wound and housed in a windingslot in its rotor. Each of the coils is wound around an axis of rotationof the rotor of the rotary transformer.

The erase circuit in FIG. 122 corresponds to the erase circuit in FIG.55. The erase circuit of FIG. 122 uses a rotary transformer in which aprimary winding (a single coil) connected to a driver circuit 126 iswound and housed in a winding slot in the stator of the rotarytransformer 127, and two secondary windings (two coils) connected toamplifiers 125a and 125b, respectively, are wound and housed in awinding slot in its rotor. Each of the coils is wound around an axis ofrotation of the rotor of the rotary transformer. A resistor R of 50 to1,000 Ω for example, preferable 150 Ω is connected across two terminalsof each of the secondary windings.

The erase circuit in FIG. 123 corresponds to the erase circuit in FIG.58. The erase circuit of FIG. 123 uses a rotary transformer in which aprimary winding (a single coil) connected to a rotary transformer drivercircuit 126 is wound and housed in a winding slot in the stator of therotary transformer 127, and four secondary windings (four coils)connected to amplifiers 125a through 125d, respectively, are wound andhoused in a winding slot in its rotor.

A record/erase circuit in FIG. 124 corresponds to the record/erasecircuit in FIG. 67. The record/erase circuit of FIG. 124 uses a rotarytransformer in which a primary winding (a single coil) connected to arotary transformer driver circuit 146 is wound and housed in a windingslot in the stator of the rotary transformer 147, and four secondarywindings (four coils) connected to erase signal amplifiers 145a and 145band record signal amplifiers 143a and 143b, respectively, are wound andhoused in a winding slot in its rotor. The output of the erase signalamplifiers 145a and 145b are connected to erasing magnetic heads E1 andE2, respectively. The output of the record signal amplifiers 143a and143b are connected to recording magnetic heads R1 and R2. The gap widthof the erasing magnetic head is for example, 4 μpm larger than that (forexample, 0.3 μm) of the recording magnetic head.

The record/erase circuit in FIG. 125 corresponds to the record/erasecircuit in FIG. 70. The record/erase circuit of FIG. 125 uses a rotarytransformer in which a primary winding (a single coil) connected to arotary transformer driver circuit 146 is wound and housed in a windingslot in the stator of the rotary transformer 147, and three secondarywindings (three coils) connected to an erase signal amplifier 145 andrecord signal amplifiers 143a and 143b, respectively, are wound andhoused in a winding slot in its rotor.

The recording/reproduction circuit in FIG. 126 corresponds to therecording/reproduction circuit in FIG. 75. The recording/reproductioncircuit of FIG. 126 uses a rotary transformer in which a windingconnected to both of a rotary transformer driver circuit 166 and anoutput amplifier 168 is wound and housed in a winding slot in the statorof the rotary transformer 167, four windings (four coils) connected toerase signal amplifiers 165a and 165b and reproduction signal amplifiers164a and 164b, respectively, are wound and housed in a winding slot inits rotor, whereas a primary winding (a single coil) connected to arotary transformer driver circuit 169 is wound and housed in a windingslot in the stator of the rotary transformer 170, and two secondarywindings (two coils) connected to record signal amplifiers 163a and163b, respectively, are wound and housed in a winding slot in its rotor.

Referring to FIGS. 127 and 128, the construction of rotary transformersused in the present invention will be explained.

In FIG. 127, a rotor 203 is mounted on a rotating shaft 202 in a lowerstationary drum 201. A stator 204 is provided coaxially with the rotor203 and mounted to the lower stationary drum 201. Above the lowerstationary drum 201, an upper stationary drum 205 is placed. A rotarydrum 206 is provided between the upper stationary drum 205 and the lowerstationary drum 201 so as to rotate together with the rotating shaft202. The rotary drum 206 has a reproduction amplifier circuit board 207mounted on its bottom and a recording circuit board 208 on its top. Therotary drum 206 is connected to the rotor 209 of a record/erase rotarytransformer. A stator 210 is provided coaxially with the rotor 209, andmounted to the upper stationary drum 205. At the top of the upperstationary drum 205, a drive circuit board 211 is mounted. Above thedrive circuit board 211, a cover 212 is provided.

FIG. 128 is a view of the reproduction amplifier circuit board 206 takenalong line A--A in FIG. 127. In FIG. 128, eight pairs of reproductionheads P1 and P2 are placed at regular intervals along the periphery ofthe board 207, those reproduction heads P1 and P2 being connected toreproduction amplifiers A1 and A2 on the board 207, respectively. Eachof the reproduction amplifiers A1 and A2 is connected to one of the twocoils housed in a winding slot in the rotor 209 as shown in FIG. 18. Inthis case, the two coils housed in a winding slot are connected to thereproduction amplifiers A1 and A1 or A2 and A2 180° opposite to eachother, respectively.

In FIG. 127, the rotary transformer has a plurality of leading holeseach formed at a position at which a wiring length between one of theamplifiers A1 and A2 and one of the leading holes is shortest, and eachof the amplifiers is connected to one of the coils inserted in a windingslot of the core of the rotary transformer through the leading holes bylead-in wires, respectively.

Next explained will be a modification of the rotary transformer,referring to FIGS. 129 through 132. In a coaxial rotary transformerapparatus of FIG. 129, a rotor 222 is provided coaxially with a stator221 so as to rotate. The upper half transformer section 223 of thistransformer is used to transfer a record signal or a reproductionsignal, whereas the lower half transformer section 224 is used totransfer an erase signal.

A single circuit winding (coil) 226 is inserted in a slot formed in theupper half portion of the stator 221 of the upper half transformersection 223, and is connected to a driver 227. A plurality of circuitwindings (coils) 229 and 230 are inserted in a slot formed in the lowerhalf portion of the rotor 222, and are connected to magnetic heads 233and 234 via a plurality of recording amplifiers 231 and 232,respectively.

Single circuit coils 237a and 237b and single circuit coils 238a and238b are inserted in slots 235a and 235b formed in the lower halfportion of the stator 221 of the lower half transformer section 224 andslots 236a and 236b formed in the lower half portion of the rotor 222,respectively. Windings (coils) 238a and 238b are connected directly toerase heads 239 and 240, respectively. Windings (coils) 237a and 237bare connected to erase drivers 241 and 242, respectively. Selectivelyoperating the erase drivers 241 and 242 switches the erase operationbetween the erase heads 239 and 240.

In the embodiment of FIG. 129, the upper half transformer section 223 isexplained as a unit transferring a record signal for convenience sake,and the same applies to the transfer of reproduction signals. Although a2-channel rotary transformer apparatus has been explained, the presentinvention may be applied to any other rotary transformer, regardless ofthe number of channels. Further, irrespective of the number of windings(coils), the invention may be applied to rotary transformers.

High-frequency band, high transfer rate VTRs such as high-vision digitalVTRs require multichannel rotary transformers, such as those with 10channels or more. To make the characteristics of each channel uniform,coaxial rotary transformers have come into use instead of the flat typewidely used in the home VTR such as VHS. Since an attempt to combinesuch coaxial rotary transformers with multiple channel specificationlengthens the transformer along the axis, so-called double coaxialtransformers have recently come into use which have multiple coaxialrotary transformers stacked coaxially. Such double coaxial transformerssacrifice the little difference between individual channels, which isthe advantage of coaxial transformers. For example, when the conditionsother than the diameter, including the number of windings (coils), theslot width, the slot depth, and the core facing width, are the same, thehigher-frequency signals are less easy to transfer and lower bandsignals are easier to transfer in a transformer with large outsidedimensions or a larger diameter. A simple way to avoid suchcharacteristic difference is to make the number of inner windings(coils) larger than that of outer windings (coils).

Since signals recorded and reproduced in the high-vision digital VTR istransferred at a transfer rate as high as 1.2 Gbps, signals of the orderof 100 MHz must be transferred by means of a single channel of therotary transformer, even if the signals are divided into 16 channels,for example. Therefore, to make the coefficient of electrostaticinduction small, coil should be wound one turn up to several turns atbest. For this reason, when the number of windings (coils) in the innertransformer is made larger than that in the outer transformer,selectable combinations are fewer and it is difficult to make thecharacteristics uniform between the inner and outer transformers becauseone turn increase or decrease causes great variations in thecharacteristics, as compared with a case where the number of windings(coils) is large, such as a case where the outer transformer has oneturn and the inner transformer has two turns, or the outer transformerhas two turns and the inner transformer has three turns.

A method of solving the above problem is to make the slot in the innertransformer of the double coaxial transformer deeper than that in theouter transformer. A transformer using this method is shown in FIG. 130.

In the double coaxial rotary transformer of FIG. 130, an outer stator252 and an inner stator 253 are placed coaxially with the rotor 251. Thedepth 257 of the inner slot is greater than the depth 254 of the outerslot in the rotor 251. The depth 256 of the slot in the inner stator 253is greater than the depth 255 of the slot in the outer stator 252.Suitably selecting those four slots can improve the characteristics ofthe inner transformer and that of the outer transformer to the extentthat they are acceptable in practical use. In this case, it is notnecessary to equalize the number of windings (coils) between the innertransformer and the outer transformer. The number of windings (coils)and the slot depth may be selected suitably as required. Similarly, theslot width and the core facing width may be selected suitably for theinner and the outer rotary transformer.

While in this embodiment, the present invention is applied to a2-channel rotary transformer, it may be applied to any other rotarytransformer, regardless of the number of channels in the rotarytransformer apparatus. The invention is not limited to double coaxialrotary transformers, but may be applied to triple coaxial transformers.

When the core facing width of the inner transformer of a double coaxialrotary transformer is made greater than that of the outer transformer,the following examples can be considered:

1. The number of channels is made the same, and the slot width of theinner transformer is made narrower than that of the outer transformer.

2. The slot width is made the same, and the number of channels in theinner transformer is made smaller than that of the outer transformer.

3. The overall slot width is made different as is the number ofchannels.

4. The slot width and the number of channels are selected as required.

Next explained will be another embodiment, referring to FIG. 131.

In this embodiment, an outer stator 252 and an inner stator 253 areplaced coaxially with a rotor 251. In this double rotary transformer,the core facing widths 260 and 261 between the inside of the rotor 251and the stator 253 are made greater than the core facing widths 258 and259 between the outside of the rotor 251 and the stator 252. By settingthose facing widths so as to be inversely proportional to the diameterof the facing portion, the characteristics of the inner and the outertransformer can be improved to the extent that they are acceptable inpractical use. In this case, it is not necessary to equalize the numberof windings (coils) between the inner transformer and the outertransformer. The number of windings (coils) and the facing width may beselected suitably as required. Similarly, the slot depth may be selectedsuitably for the inner and outer transformers.

While in this embodiment, the present invention is applied to a2-channel rotary transformer, it may be applied to any other rotarytransformer, regardless of the number of channels in the rotarytransformer apparatus. The invention is not limited to double coaxialrotary transformers, but may be applied to triple coaxial rotarytransformers.

For the signal recorded and reproduced by the high-vision digital VTR,the characteristics are, of course, expected to be flat over therequired band. Thus, it is necessary to apply damping to suppressresonance. In this case, ideally, the resonance point should be sethigher than the necessary highest frequency. Since the transfer rate isas high as 1.2 Gbps, the signal of the order of 100 MHz must betransferred by means of a single channel in the rotary transformer, evenif signals are divided into 16 channels, for example. As a result, therearise a situation where the characteristics must be held flat for use upto a frequency exceeding the resonance point.

In such a high frequency band, resonance takes place due to the couplinginductance of the rotary transformer, the receiver, and the capacitancearound them. Further, resonance develops due to, for example, leaks inthe rotary transformer, the inductance, the floating capacitance in thecircuits on the rotary transformer input side, and the capacitancebetween the primary winding and the secondary winding of the rotarytransformer. Practically, to obtain a wide band, it is necessary toeliminate those resonances simultaneously.

A method of solving the above problem is to make the depth of the slotin the inner transformer of a double coaxial rotary transformer greaterthan that of the outer transformer and, at the same time, determine thedepth of the slots so that the capacitance between the primary windingand the secondary winding may be optimal.

Another problem is that since the signal recorded and reproduced by thehigh-vision VTR has a transfer rate as high as 1.2 Gbps, the signal ofthe order of 100 MHz must be transferred by means of a single channel ofthe rotary transformer, even if signals are divided into 16 channels,for example. As a result, there arise a situation where thecharacteristics must be held flat for use up to a frequency exceedingthe resonance point.

In this case, measures are taken to basically place the stator winding(coil) closer to the rotor winding (coil) to improve the transfercharacteristics over a wide band. Here, to place the winding as close tothe surface of the slot as possible, the ease of winding is sacrificedto make the winding slot shallower or the core facing surfaces areground after the placement of windings. In the coaxial rotarytransformer, since either the rotor or the stator has the winding coilwound from the inside, it is very difficult to wind the winding coilwhen the slot is shallow.

A way to solve the above problem is to provide a dielectric between therotor winding and the stator winding. This embodiment will be explained,referring to FIG. 132.

In FIG. 132, a dielectric 262 is placed at the core facing surface in aslot in the rotor 262, and a dielectric 263 is place at the outer corefacing surface in a slot in the stator 261. This provide the same effectas placing the rotor winding coil closer to the stator winding coil,even if the winding coil is placed deeper in the deepened slot, whichmakes it easier to wind the winding coil. Further, by manufacturing acore separated along line 264, placing a dielectric at the core facingsurface, inserting a winding coil in the core, and then the separatedcore portion is attached to the core body, the winding coil can be woundaround the core easily.

The rotary transformers shown in FIGS. 129 to 132 may be applied to therecording and reproduction apparatuses according to the above variousembodiments and the following embodiments. Also, the stator and rotormay be exchanged in structure. That is, the structure of the stator maybe used as the rotor and vice versa.

Next explained will be a 180°-switching rotary transformer-mountedcircuit control apparatus, which controls a recording circuit, areproduction circuit, and an erase circuit mounted on a rotary drum asmentioned above.

In FIG. 133, reproduction heads P1 and P2 are placed 180° opposite toeach other on the circumference of a rotary drum. Reproductionphotodetectors 271a and 271b are mounted on the rotary drum along a lineconnecting the reproduction heads P1 and P2 radially.

On the stationary drum, a reproduction LED array 272, which is composedof a number of LEDs arranged in a circular arc along the direction ofrotation of the rotary drum, is positioned over the effectivereproduction area, in this case, over an angle of θ1, approximately180°, for example, 178° with respect to a rotational direction of therotary drum, in a location that allows them to face the photodetectors271a and 271b as the rotary drum rotates. A magnetic tape is woundaround the rotary drum at a wrap angle θ2 of 200° with respect to arotational direction of the rotary drum. The angle θ1 corresponding tothe effective reproduction area is called the effective wrap angle, andthe wrap angle θ2 is called the total wrap angle.

The relation between the wrap angle and the number of magnetic heads isdescribed referring to FIGS. 78A to 79B. When two magnetic heads to besequentially activated are mounted on said rotary drum, the total wrapangle is set at more than 180°, when three magnetic heads are mounted onthe rotary drum, the total wrap angle is set at more than 120°, and whenfour magnetic heads are mounted on the rotary drum, the total wrap angleis set at more than 90°.

Referring to FIGS. 134 through 140, various methods of placing LEDarrays will be explained, using the reproduction LED array 272 as anexample.

In FIG. 134, a plurality of LED bare chips constituting the LED array272 are mounted on an LED board 401, and connected to the wiring patternon the LED board 401 with bonding wires and to a reproduction controlcircuit. The LED array 272 is placed within a semicircular slot 403formed in one side of the stationary drum 400 facing the rotary drum(not shown), along the direction of rotation of the rotary drum. Byconstructing in this way, rays of light emitted from the LED array 272converge efficiently in the direction perpendicular to the LEDarrangement direction to form a circular arc of a narrow luminous flux.

FIG. 135 shows an example of mounting a plurality of LED bare chipsconstituting the LED array 272 on an LED board 401 attached to the backof the stationary drum 400, and placing those LED bare chips in asemicircular through hole 404 bored in the stationary drum 400. Thisconfiguration provides the same effect as that of FIG. 134.

FIG. 136 shows an example of filling the through hole 404 of FIG. 135with a resin 405. The resin 405 may be a transparent material, amaterial which presents a large transmittance at the light-emittingwavelength of the LED, or even a resin mixed with a light diffusant. Thelinear light emission caused by the LED array has ripples in the amountof light proportional to the number of LEDS. By mixing a light diffusantwith the resin 405 to diffuse rays of light from the LEDs, such ripplesin the light amount can be decreased.

FIG. 137 shows an example of placing on one side of the stationary drum400 a light diffusing sheet 406 made up of a material such as a resinwhich presents a large transmittance at the light-emitting wavelength ofthe LED. Use of the light diffusing sheet 406 decreases such ripples inthe light amount for the LED array, as with a light diffusant mixed withthe resin 405 of FIG. 136.

FIG. 138 shows an example of tapering the walls of the through hole 404so as to fan out in the light-emitting direction in order to increasethe converging efficiency. FIG. 139 shows an example of tapering thewalls of the through hole 404 so as to fan out in the opposite directionto the light-emitting direction in order to increase the convergingefficiency. Depending on the VTR system used, either the FIG. 138configuration or the FIG. 139 configuration may be used.

FIG. 140 shows an example of placing above the through hole 404 of FIG.135 a semicircular cylindrical lens 407 for more efficiently convergingrays of light from the LED array 272 and enabling linear light emissionover the effective recording area. The cylindrical lens is produced byinjection-molding a transmittable resin, such as an acrylic acid resin,a polycarbonate resin, amorphous polyolefin, a styrene resin, a urethaneresin, or an epoxy resin, and is mounted by fitting it into or bondingit to the one side of the stationary drum 400.

When LEDs constituting the LED array 272 cause failure because of theexpiration of service life, for example, and emit no light, it isnecessary to inform the system controller of the VTR system and theoperator of the failure to urge him to take proper measures such asreplacement. Since the LED array is composed of a lot of LED bare chips,it is desirable that when as few as one or two LED chips fail, the LEDarray as a whole should operate as expected. Embodiments taking intoaccount measures to deal with LED failures will be explained, referringto FIGS. 141A through 142B.

FIG. 141A shows an example of connecting a plurality of LEDs D1 throughDx at intervals of four LEDS. FIG. 141B is what FIG. 141A is redrawn forthe sake of clarity. LED groups of LEDs series-connected at intervals offour LEDs are indicated by numerals 410 through 413. Current determiningresistances R10 through R13 are connected to the groups 410 through 413,respectively.

By doing this, even if a relatively small number of LEDs, as few as oneor two, fail, linear light emission of a specified amount of light canbe made without any problem. For example, if one LED fails in LED group410, all the LEDs in LED group 410 go off, but the remaining LED groups411 through 413 emit light. As a result, although the amount of lightdecreases at the place corresponding to the individual LEDs in LED group410, the decreased amount can be compensated by raising the power supplyvoltage Vcc by the corresponding amount on the part of the systemcontroller. By using a constant-current circuit as the driving sourcefor the LEDs, which allows the current flowing to the remaining LEDgroups to increase by as much current as ceased to flow in LED group 410that has gone off, the amount of light can be increased.

FIG. 142A shows an example of using a photocoupler 420 in place of theoperation-check visible-light LED, connecting an LED 421 in thephotocoupler 420 in series with the LED array (LEDs D1 through Dx), andallowing a photodetector 422 in the photocoupler 420 to senseabnormalities in the LED array. While the photocoupler 420 uses aphototransistor for the photodetector 421, a photodiode or otherlight-receiving elements such as photo ICs may be used instead.Resistance R14 is a current-determining resistance which determinescurrent flowing through LEDs D1 through Dx. Resistance R15 is acurrent-determining resistance which determines the current that flowsthrough the photodetector 422 when the output goes to a low (L) level atthe switching of the photodetector 422.

In FIG. 142A, by keeping the voltage of the power supply Vcc2 at 5 V, itis possible to supply the output of the photocoupler 420 directly to thecontrol circuit of a VTR using digital ICs such as TTL logic ICs or MOSlogic ICs.

The operation of the FIG. 142A circuit will be explained briefly. Duringa normal operation, current flows properly to cause LEDs D1 through Dxto emit light. At this time, LED 421 in the photocoupler 420 also emitslight, which causes the photodetector 422 to turn on, bringing Y point,the output terminal of the photodetector 420 into the L level. If anyone of LEDs D1 through Dx fails, which prevents the current driving LEDsD1 through Dx from flowing, stopping the light emission, with the resultthat LED 421 in the photocoupler 420 also ceases to emit light. Thismakes the photodetector 422 of the photocoupler 420 turn off, placingpoint Y at a high level. Therefore, it is found that LEDs D1 through Dxoperate properly when point Y is at the L level, and are defective whenpoint Y is at the H level. The control circuit judges the level of pointy and informs the operator of LED failure alarm.

FIG. 142B shows an example of connecting a visible light LED Da inseries with LEDs D1 through Dx, the LED 421 in the photocoupler 420, andresistance R14 for easy visual inspection.

FIG. 143 is a sectional view schematically showing a package internalconstruction where the MCP system is applied to the present invention.In this packaging method, a conventional IC package contains a pluralityof ICs or discrete elements such as hetero-semiconductor processed barechips, and passive elements including capacitances and resistances putin silicon chips, by means of special lead frames, which areinterconnected each other on the wiring board on the lead frame, andarmored in a transfer mold.

This arrangement and manufacturing method will be explained briefly.First, a wiring board 601 is bonded to an IC lead frame 600 with anadhesive 602, on which an IC 603 and a photodetector 604 of therecording circuit in a bare chip are bonded with a conductive adhesive605. Those are connected to each other by bonding wires via the wiringpattern 606 on the wiring board 601. After that, by transfer moldsealing, a hybrid IC package 608 is formed. A lens 609 for convergingrays of light from the LED may be formed integrally with the package608.

In this way, the system of putting the recording circuit, photodetector,and the related circuits in the same hybrid IC can be applied to othertypes of scanners.

FIG. 144 is a block diagram of a recording circuit with a carriersensing function. This recording circuit uses a full-wave rectifying RFdetector 720 as an RF detector acting as information signal sensingmeans. Specifically, the record RF signal transferred from the rotarytransformer (not shown) is supplied to input 1 and input 2 of therecording circuit 713a. The supplied record RF signal is amplified by anamplifier 721a and divided into two signals, one of which is supplied toa full-wave rectifying recording RF detector 720, and the other of whichis supplied to an amplifier 727 via an amplifier 721b. The full-waverectifying RF detector 720, which is composed of a full-wave rectifiercircuit, supplies a high (H) level signal to an AND gate at the nextstage.

FIG. 145 shows a construction of the full-wave rectifying RF detector720, which is composed of a full-wave rectifier circuit 728, a low-passfilter 729, and a comparator 724. The operation of the RF detector 720will be explained, referring to waveform diagrams in FIG. 146. Tosimplify the explanation, the RF signal supplied to the RF detector 720is assumed to be a sine wave.

The RF signal shown in FIG. 146 is converted into the components lowerand higher than the fundamental frequency of the RF signal by thefull-wave rectifier circuit 728, which rectifies the RF signal into afull-wave rectified output. The full-wave rectified output from thefull-wave rectifier circuit 728 is supplied to the low-pass filter 729,which removes the higher frequency components to ex tract only the lowerfrequency components, thereby providing a low-pass filter output. Theoutput from the low-pass filter 729 is supplied to a comparator 724,which binarizes it.

Use of the full-wave rectifying detector 709 shown in FIG. 145 offersthe following advantages.

After the RF signal is converted into the components lower and higherthan its fundamental frequency by the full-wave rectifier circuit 728,the higher frequency components are removed by the low-pass filter 729and the resulting signals are supplied to the comparator 724. Thisenables the cut-off frequency of the low-pass filter 729 to be sethigher than the fundamental frequency of the RF signal, which makes itpossible to the capacity of the capacitor used for the low-pass filter729 smaller. The formation of the capacitor in the IC does not make thechip size larger. The reduction in the capacitor capacity shortens thecharging and discharging time, making the RF signal sensing speedfaster.

In the case of HDTV digital VTRs, a recording rate per magnetic head is148.5 Mbps, as written in the Journal of "Broadcasting Technology,"November special issue, Vol. 43, No. 12, 1990, pp. 20-26 and pp. 62-66.In the record modulation system, although use of 8--8 conversion ASEcodes suppresses the lower-frequency components as much as possible, notall lower-frequency components are eliminated completely. Therefore, theRF detector must sense RF signals over a wide band ranging from lowerfrequencies to as high as 148.5 Mbps. Since the HDTV digital VTR uses asmany magnetic heads as 18, as mentioned earlier, this imposes a severerestriction on the circuit mounting area of the rotary drum. For thisreason, it is absolutely necessary to produce the RF detector in IC formand its chip size is desired to be as small as possible with thefull-wave rectifying RF detector 720 constructed as described above, itis possible to meet these requirement easily.

FIG. 147 shows another construction of the full-wave RF detector 720,which differs from that in FIG. 144 in that there are two stages offull-wave rectifier circuits 728a and 728b. FIG. 148 is operatingwaveform diagrams for the FIG. 147 RF detector 720. After the RF signalis rectified into a first-stage full-wave rectified output by afirst-stage full-wave rectifier circuit 728a and then rectified into asecond-stage full-wave rectified output by a second-stage full-waverectifier circuit 728b, the higher-frequency components are removed fromthe resulting RF signal by the low-pass filter 729 to produce a low-passfilter output.

As evident from FIG. 148, the higher-frequency components in thesecond-stage low-pass filter output from the second-stage full-waverectifier circuit 728b are converted into frequency components whosefrequencies are higher than those of the first-stage low-pass filteroutput of the first-stage full-wave rectifier circuit 728a. Byperforming full-wave rectification over two stages, it is possible tomake the capacity of the capacitor used for the low-pass filter 729smaller than that in a single stage of a full-wave rectifier circuit(FIG. 144).

FIG. 149 shows another construction of the full-wave rectifying RFdetector 720, which has a high-pass filter 730 inserted between twostages of the full-wave rectifier circuits 728a and 728b of FIG. 147.FIG. 150 is operating waveform diagrams for the FIG. 147 RF detector720. After the RF signal in FIG. 150 is rectified into a full-waverectified output by the first-stage full-wave rectifier circuit 728a,only the higher-frequency components are extracted from the resultingsignal to produce a high-pass filter output. After the output of thehigh-pass filter 730 is rectified into the second-stage full-waverectified output by the second-stage full-wave rectifier circuit 728b,the higher-frequency components are removed from the resulting signal bythe low-pass filter 729 to produce a low-pass filter output.

The high-pass filter 730 can improve the effect of full-waverectification by the second-stage full-wave rectifier circuit 728b byremoving the direct-current component of the output of the first-stagefull-wave rectifier circuit 728a. Further, the high-pass filter 730helps to increase the response speed to the RF signal of the output ofthe low-pass filter 729, especially the rising response speed. Since thehigh-pass filter 730 does not require a capacitor of a largecapacitance, it is possible to make IC chips more compact without anytrouble.

FIG. 151 shows another construction of the full-wave rectifying RFdetector 720, which has a limiter amplifier 770 at the stage precedentto the full-wave rectifier circuit 728 of FIG. 145.

FIG. 152 is operating waveform diagrams for the FIG. 151 RF detector720. The sinusoidal RF signal of FIG. 152 is limited in amplitude by thelimiter amplifier 770 and shaped into a square wave with a sharp risingedge and a sharp falling edge to produce a limiter output. The output ofthe limiter amplifier 770 is rectified into a full-wave rectified outputby the full-wave rectifier circuit 728. After the low-pass filter 729removes the higher-frequency components from the resulting signal, thelow-pass filter output is supplied to the comparator 24 forbinarization.

As seen from the comparison of the waveforms in FIG. 146 and those inFIG. 152, ripples in the output of the full-wave rectifier circuit 728are smaller than those in the full-wave rectified output of the FIG. 151RF detector. This is because in FIG. 151, the input to the full-waverectifier circuit 728 is converted into a square wave, whereas in FIG.145, the input to the full-wave rectifier circuit 728 is sinusoidal.Thus, with the arrangement of FIG. 151, it is possible to make smallerthe capacitance of the capacitor used for the low-pass filter 729 forremoving ripples in the output of the full-wave rectifier circuit 728.

The arrangement of the FIG. 151 full-wave rectifying RF detector 720 iseffective not only for a sinusoidal RF signal but also a square RFsignal such as an NRZ signal, for example. Such a square RF signalbecomes dull in wave form as its direct-current component drops whenpassing through the rotary transformer. The limiter amplifier 770,however, can return the dull waveform to a sharp square waveform.

This effect will be explained, referring to FIG. 153. FIG. 153 isoperating waveform diagrams when the RF signal input is of a squarewaveform. The RF signal is an NRZ signal, which becomes alower-frequency cut signal with the direct-current component droppedafter passing through the rotary transformer. The lower-frequency cut RFsignal is supplied to the limiter amplifier 770, which shapes it into asquare-wave limiter output. The limiter output is rectified into afull-wave rectified output by the full-wave rectifier circuit 728. Afterthe low-pass filter 729 removes ripples from the resulting signal, thelow-pass filter output is supplied to the comparator 724.

In this way, with the arrangement of FIG. 151, it is possible toproperly sense the RF signal, regardless of the type of RF signalwaveform.

Similar effects, of course, can be obtained even when the limiteramplifier 770 and the full-wave rectifier circuit 728 are reversed intheir position.

FIG. 154 shows another construction of the full-wave rectifying RFdetector 720. In this example, means for eliminating thehigher-frequency components after the full-wave rectification at theFIG. 151 RF detector 720 is realized without using the low-pass filter729. In FIG. 154, the output of the full-wave rectifier circuit 728 isfirst supplied to the comparator 724, and then processed at a delaycircuit 771 and an OR gate 772. FIG. 155 is operating waveform diagramsfor the FIG. 154 RF detector 720.

The RF signal in FIG. 155 is processed in sequence into a limiter outputand a full-wave rectified output by the limiter amplifier 770 and thefull-wave rectifier circuit 728, respectively, as shown in FIG. 151. Thefull-wave rectified output of the full-wave rectifier circuit 728 isbinarized by the comparator 724. The comparator output of the comparator724 is divided into two signals, one of which is supplied to the delaycircuit 771 that delays it, and the other of which is supplied to oneinput of the OR gate 772. The output of the delay circuit 771 issupplied to the other input of the 0R gate 772. The output of the ORgate 772 is the RF signal sense output.

Since the example of FIG. 154 requires neither low-pass filter nor ahigh-pass filter, this makes the response speed of the OR gate output orthe RF signal sense output to the RF signal very fast. Additionally, acapacitor used as a filter element is not necessary. These features aremore effective in fabricating ICs.

Referring to FIGS. 156 through 158, the construction and operation ofanother embodiment of the recording circuit will be explained.

FIGS. 157 and 158 illustrate the operation sequence for various portionsof the FIG. 156 recording circuit during a normal recording operationand during an insert recording operation, respectively. In the record RFsignal (a), a switch control signal inserted at the head of each of R1record signal and R2 record signal has a greater amplitude than that ofthe record signal, each amplitude being equal. FIG. 156 shows an exampleof the recording circuits 713a and 723b, which perform control using aswitch control signal sensed by signal amplitude sensing means thatsenses from the record RF signal the difference in amplitude between therecord signal and the switch control signal.

In FIG. 156, the record RF signal transferred from the rotarytransformer is supplied to input 1 and input 2 of the recording circuits713a and 713b. The supplied record RF signal is divided into threesignals, which are supplied to an emitter follower 781, a carrier sensecircuit 782, and a signal amplitude sense circuit 783, respectively.

The carrier sense circuit 782 transmits a high (H) level signal to anAND gate 788 as long as the signals including the switch control signalare being supplied. As the carrier sense circuit 782, the full-waverectifying RF detectors shown in FIGS. 145 through 155 may be used.

The signal amplitude sense circuit 783 places the output at the H levelonly during the time when a signal whose amplitude is larger than thatof the record signal by a specified amplitude level is sensed. It thentransmits the resulting signal as the switch control signal to aninverter 784 and a flip-flop 786. The signal amplitude sense circuit 783can be constructed in a similar manner to the carrier sense circuit, bymodifying the signal amplitude level to be sensed.

When the switch control signal is sensed and the output of the signalamplitude sense circuit 783 is at the H level, the inverter 784transmits a low (L) level signal to the AND gate 788. At this time, theAND gate 788 supplies a L-level signal to an output off circuit 789,which places an amplifier 790 in an inactive state, thereby preventingthe switch control signal in the record RF signal from being supplied asa recording current.

An initial setting circuit 785 is a circuit that transmits a H levelsignal to the MR (master reset) input of the flip-flop 786 only at thetime when power is turned on, in order to reset the state of the Qoutput of the flip-flop 786 to a L level immediately after the turningon of the power supply.

The flip-flop 786 is a T flip-flop with a master reset input in thisembodiment. It keeps the Q output state at the H level or the L levelduring the time from when the switch control signal sensed by the signalamplitude sense circuit 783 is transmitted to T input until the nextswitch control signal is transmitted. The state of Q output is invertedeach time the switch control signal is supplied.

An EX-OR (exclusive OR) gate is a circuit for causing the recordingcircuit to operate either as the recording circuit 713a for driving themagnetic head R1 or as the recording circuit 713b for driving themagnetic head R2. The EX-OR gate 787 produces a H-level output when itstwo inputs are at different levels, and a L-level output when its twoinputs are at the same level. For example, when one input is fixed atthe L level, the output is at the L level when the other input is at theL level, and the output is at the H level when the other input is at theH level. That is, a change in the input state directly appears at theoutput. When one input is fixed at the H level, the output is at the Hlevel when the other input is at the L level, and the output is at the Llevel when the other input is at the H level. That is, the inversion ofa change in the input stage appears at the output.

When the Q output of the flip-flop 786 is supplied to the AND gate 788,the above action is used to switch the operation of the recordingcircuit either to transmit the output state directly or to invert andtransmit the state. When the operation switching input is fixed at the Llevel, the Q output of the flip-flop 786 is supplied directly. When itis fixed at the Hi level, the Q output is inverted and supplied. Theformer operates as the recording circuit 713a to drive the magnetic headR1, and the latter operates as the recording circuit 713b to drive themagnetic head R2. This makes it possible to prevent the two recordingcircuits of the same construction 180° opposite to each other fromoperating simultaneously.

When the signals supplied from the carrier sense circuit 782, theinverter 784, and the EX-OR gate 787 are all at the H level, the ANDgate 788 supplies a H-level signal to the output off circuit 789 to makethe amplifier active.

Referring to FIGS. 157 and 158, the operation sequence of variousportions of the FIG. 156 recording circuit during a normal recordingoperation and during an insert recording operation will be explained.

The record RF signal (a) transferred from the rotary transformer issupplied to input 1 and input 2 of the recording circuits 713a and 713b.The record RF signal (a) is divided into three signals, which aresupplied to the emitter follower 781, the carrier sense circuit 782, andthe signal magnitude sense circuit 783, respectively. The output (b) ofthe carrier sense circuit 782 is kept at the H level as long as thesignals including the switch control signal are being supplied. Theoutput (c) of the signal amplitude sense circuit 783 is at the H levelonly when the switch control signal is sensed. The output (c) of thesignal amplitude sense circuit 783 is inverted by the inverter 784 toproduce a signal amplitude sense circuit inverted signal (c'). Becauseof this, while the switch control signal is being sensed, the switchingsignal (e1, e2), i.e. the output of the AND gate 788, is at the L level.During this period of time, the output off circuit 789 makes theamplifier 790 inactive, preventing the switch control signal in therecord RF signal from being supplied as a recording current.

The Q output of the flip-flop 786 in the L-level state reset by theinitial setting circuit changes to the H level when the first switchcontrol signal, or the switch control signal at the head of the R1record signal, is sensed and the output (c) of the signal amplitudesense circuit 783 rises to the H level. The Q output changes to the Llevel when the second switch control signal, or the switch controlsignal at the head of the R2 record signal, is sensed and the output (c)of the signal amplitude sense circuit 783 rises to the H level again.Similarly, from this time on, the Q output of the flip-flop 786 isinverted each time the switch control signal is sensed.

In the recording circuit 713a, since the Q output of the flip-flop 786appears directly at the output (d1) of the EX-OR gate 787, the latteroutput is at the H level when an odd number-th switch control signal issensed, and is at the Lo level when an even number-th switch controlsignal is sensed. The switching signal (e1) goes to the H level when allthe inputs to the AND gate 788 are at the H level, or when the output(b) of the carrier sense circuit 782, the signal amplitude sense circuitinverted output (c'), and the output (d1) of the EX-OR gate 787 are allat the H level. Since the output OR circuit 789, when the switch signal(e1) is at the H level, makes the amplifier 90 active, the recordingcurrent corresponding to R1 record signal is supplied as shown by the R1recording current (f1), while the recording current corresponding to theR2 record signal is not supplied.

In the recording circuit 713b, since the inversion of the Q output ofthe flip-flop 786 appears at the output (d2) of the EX-OR gate 787, thelatter output is at the L level when an odd number-th switch controlsignal is sensed, and is at the H level when an even number-th switchcontrol signal is sensed. The switching signal (e2) goes to the H levelwhen all the inputs to the AND gate 788 are at the H level, or when theoutput (b) of the carrier sense circuit 782, the signal amplitude sensecircuit inverted output (c'), and the output (d2) of the EX-OR gate 787are all at the H level. Since the output OR circuit 789, when theswitching signal (e2) is at the H level, makes the amplifier 90 active,the recording current corresponding to R1 record signal is not suppliedas shown by the R2 recording current (f2), while the recording currentcorresponding to R2 record signal is supplied.

Similarly, during an insert recording operation, partial rewriting canbe done by using the switch control signal added to the heads of R1record signal and R2 record signal to control the switching of therecording circuit 713a and 713b so as to record only the signals to beinsert-recorded by the carrier sense circuit.

This embodiment also provides the same effect as does the precedingembodiment. With this embodiment, the recording circuits 713a and 713bcan be switched to one another without using recording circuit controlmeans composed of an LED array and a photodetector. Since it is notnecessary to provide a special rotary transformer and channels includingslip rings to transfer the switch control signal, the circuitconfiguration of the VTR's recording system can be made simpler and morecompact without sacrificing the normal recording operation, partialrewriting only onto the video tracks, and partial rewriting onto theaudio tracks.

Referring to FIG. 159, another recording circuit will be explained.FIGS. 160 and 161 show the operation sequence of various portions of theFIG. 159 recording circuit during a normal recording operation andduring an insert recording operation.

In the record RF signal (a), a switch control signal is inserted at thehead of R1 record signal but not at the head of R2 record signal toprovide a null signal period between R1 record signal and R2 recordsignal. The switch control signal is sensed by signal amplitude sensingmeans as with the first embodiment and used as a first switch controlsignal. The null signal period of the record RF signal is sensed bycarrier sensing means and used as a second switch control signal. Thisembodiment provides a recording circuit that performs switching controlusing two switch control signals.

This embodiment differs from the recording circuit shown in FIG. 156 inthat an RS flip-flop is used for the flip-flop 786, which is controlledby the first switch control signal from the signal amplitude sensecircuit 783 and the second switch control signal, the output signal fromthe carrier sense circuit 782 inverted by the inverter 791, and that useof this control system eliminates the initial setting circuit. Since theconstruction of the remaining circuit is the same as that of therecording circuit shown in FIG. 156, its explanation will be omitted.

In FIG. 159, when the RF signal is in the null signal state, the outputof the carrier sense circuit 782 is at the L level, and the output ofthe inverter, the second switch control signal, is inverted into the Hlevel.

The R input of the flip-flop 786 is supplied with a H level signal fromthe inverter 791, and the Q output of the flip-flop 786 is reset to theL level. The Q output of the flip-flop 786 is maintained until theoutput of the signal amplitude sense circuit 783, the first switchcontrol signal, is at the H level and supplied to the S input. When theH-level signal is supplied to the S input, the Q output of the flip-flop786 is set at the H level. The Q output of the flip-flop 786 is keptuntil the carrier sense circuit 782 senses the null signal state, placesthe output of the inverter 791, the second switch control signal, at theH level and this high level output is supplied to the R input.

Since the Q output of the flip-flop 786 is always reset to the L levelas long as the record RF signal is in the null signal state, the initialsetting circuit used in the recording circuit in FIG. 156 is notnecessary. The operation of the remaining circuit is the same as therecording circuit of FIG. 156.

Referring to FIGS. 160 and 161, the operation sequence of variousportions of the FIG. 159 recording circuit during a normal recordingoperation and during an insert recording operation will be explained.

The record RF signal (a) transferred from the rotary transformer issupplied to input 1 and input 2 of the recording circuits 713a and 713b.The record RF signal (a) is divided into three signals, which aresupplied to the emitter follower 781, the carrier sense circuit 782, andthe signal amplitude sense circuit 783, respectively.

The output (b) of the carrier sense circuit 782 is at the H level whilethe signals including the switch control signal are being supplied, andat the L level before and after the record RF signal is supplied andduring the time of period when R1 record signal and R2 record signal arenull signals. The output (b) of the carrier sense circuit 782 isinverted by the inverter 791 to produce a carrier sense circuit invertedoutput (b').

The output (c) of the signal amplitude sense circuit 783 is at the Hlevel only when the switch control signal is sensed. The output (c) ofthe signal amplitude sense circuit 783 is inverted by the inverter 784to produce a signal amplitude sense circuit inverted signal (c').Because of this, while the switch control signal is being sensed, theswitching signal (e1, e2), i.e. the output of the AND gate 788, isplaced at the L level. During this period of time, the output offcircuit 789 makes the amplifier 790 inactive, preventing the switchcontrol signal in the record RF signal from being supplied as arecording current.

The Q output of the flip-flop 786 in the initial state reset with norecord RF signal is set to the H level when the first switch controlsignal, or the switch control signal at the head of R1 record signal, issensed and the output (c) of the signal amplitude sense circuit 783rises to the H level. The Q output is reset to the L level when the nullsignal period at the head of R2 record signal, is sensed and the carriersense circuit inverted output (b') rises to the H level. Similarly, fromthis time on, the Q output of the flip-flop 786 is inverted by thealternate setting and resetting by the signal amplitude sense circuitoutput (c) 783 and the carrier sense circuit inverted output (b').

In the recording circuit 713a, since the Q output of the flip-flop 786appears directly at the output (d1) of the EX-0R gate 787, the latteroutput is at the H level when the switch control signal at R1 recordsignal is sensed, and is at the L level when the null signal period atthe head of R2 record signal is sensed. The switch signal (e1) goes tothe H level when all the inputs to the AND gate 788 are at the H level,or when the output (b) of the carrier sense circuit 782, the signalamplitude sense circuit inverted output (e'), and the output (d1) of theEX-OR gate 787 are all at the H level. Since the output off circuit 789,when the switching signal (e1) is at the H level, makes the amplifier790 active, the recording current corresponding to R1 record signal issupplied as shown by the R1 recording current (f1), while the recordingcurrent corresponding to R2 record signal is not supplied.

In the recording circuit 713b, since the inversion of the Q output ofthe flip-flop 786 appears at the output (d2) of the EX-OR gate 787, thelatter output is at the L level when the switch control signal at thehead of R1 record signal is sensed, and is at the H level when the nullsignal period at the head of R2 record signal is sensed. The switchingsignal (e2) goes to the H level when all the inputs to the AND gate 88are at the H level, or when the output (b) of the carrier sense circuit782, the signal amplitude sense circuit inverted output (e'), and theoutput (d2) of the EX-OR gate 787 are all at the H level. Since theoutput off circuit 789, when the switch signal (e2) is at the H level,makes the amplifier 790 active, the recording current corresponding toR1 record signal is not supplied as shown by the R1 recording current(f2), while the recording current corresponding to R2 record signal issupplied.

Similarly, during an insert recording operation, partial rewriting canbe done by using the first switch control signal added to the head of R1record signal and the null signal period at the head of R2 record signalto control the switching of the recording circuits 713a and 713b so asto record only the signals to be insert-recorded by the carrier sensecircuit 782.

Referring to FIG. 162, the construction of another recording circuitwill be explained. Referring to FIGS. 163 and 164, the operationsequence of various portions of the FIG. 162 recording circuit during anormal recording operation and during an insert recording operation willbe explained.

In the record RF signal (a) of this recording circuit, the first switchcontrol signal inserted before and after R1 record signal (hereinafter,referred to as the R1 switch control signal) has a larger amplitude thanthat of the second switch control signal inserted before and after R2record signal (hereinafter, referred to as the R2 switch controlsignal). This embodiment provides a recording circuit which senseseither R1 switch control signal or R2 switch control signal on the basisof the amplitude difference between them. For example, the recordingcircuit 713a senses R1 switch control signal to switch between theactive and inactive states, and the recording circuit 713b senses R2switch control signal to switch between the active and inactive states.

The record RF signal transferred from the rotary transformer is suppliedto input 1 and input 2 of the recording circuits 713a and 713b. Thesupplied record RF signal is divided into two signals, one of which issupplied to an emitter follower 781 and the other of which is suppliedto a signal amplitude sense circuit 783.

The signal amplitude sense circuit 783 of the recording circuit, whosefunction differs from that of the recording circuits of FIGS. 156 and159, has the upper and lower limits of comparison reference to sense theamplitude difference between the record signal, R1 switch control signaland R2 switch control signal contained in the record RF signal, producesa Hi-level signal when the amplitude level of the signal lies within thelimit range and a L-level signal when the level exceeds the range. Forexample, in the case of the record RF signal (a) of FIG. 163, by settingthe upper limit larger than the amplitude of R1 switch control signaland by setting the lower limit smaller than the amplitude of R2 switchcontrol signal, R1 switch control signal can be sensed. Further, bysetting the upper limit larger than the amplitude of R2 switch controlsignal whose amplitude is smaller than that of R1 switch control signaland by setting the lower limit larger than the amplitude of the recordsignal, R2 switch control signal can be sensed.

The sensing level setting input is fixed to a suitable potential. Bychanging the potential, it is determined whether R1 switch controlsignal or R2 switch control signal is sensed. The recording circuit thatsenses the former operates as the recording circuit 713a and therecording circuit that senses the latter operates as the recordingcircuit 713b. This prevents the recording circuits of the sameconfiguration 180° opposite to each other from operating simultaneously,which eliminates the EX-OR gate 87 used in the previous embodiment.

Since the recording circuit 713a of FIG. 162 records only the R1 recordsignal sandwiched by R1 switch control signals and the recording circuit713b records only the R2 record signal sandwiched by R2 switch controlsignals, it is not necessary to perform control using the carrier sensecircuit in order to supply only the signal to be recorded.

The inverter 784, initial setting circuit 785, and flip-flop 786 havethe same construction as those in the recording circuit of FIG. 156, andfunction in the same manner.

The AND gate 788 differs from those in FIGS. 156 and 159 in that it hastwo inputs because the carrier sense circuit is removed. The AND gate788, when both the signals sent from the inverter 784 and flip-flop 786are at the H level, supplies a H-level signal to the output off circuit789, making the amplifier 790 active.

Referring to FIGS. 163 and 164, the operation sequence of variousportions of the FIG. 162 recording circuit during a normal recordingoperation and during an insert recording operation will be explained.

The record RF signal (a) transferred from the rotary transformer issupplied to input 1 and input 2 of the recording circuits 713a and 713b.The record RF signal (a) is divided into two signals, one of which issupplied to the emitter follower 781 and the other of which is suppliedto the signal amplitude sense circuit 783.

In the case of the recording circuit 713a, the output (c1) of the signalamplitude sense circuit 783 goes to the H level when R1 switch controlsignal is sensed. The output (c1) of the signal amplitude sense circuit783 is inverted by the inverter 784 to produce a signal amplitude sensecircuit inverted signal (e1'). Because of this, while the R1 switchcontrol signal is being sensed, the switching signal (e1), the output ofthe AND gate 788, is placed at the L level. During this period of time,the output off circuit 789 makes the amplifier 790 inactive, preventingthe switch control signal in the record RF signal from being supplied asa recording current.

The Q output (d1) of the flip-flop 786 reset to the L level goes to theHi level when the switch control signal at the head of R1 record signalis sensed. The Q output goes to the L level when the switch controlsignal at the end of R1 record signal is sensed. Because no R2 switchcontrol signal is sensed, there is no change in the Q output. Similarly,from this time on, the Q output of the flip-flop 786 is inverted eachtime the R1 switch control signal is sensed.

The switch signal (e1) goes to the H level when all the inputs to theAND gate 788 are at the H level, or when the signal amplitude sensecircuit inverted output (e1') and the output (d1) of the flip-flop 786are all at the H level. Since the output off circuit 789, when theswitching signal (e1) is at the H level, makes the amplifier 790 active,the recording current corresponding to R1 record signal is supplied asshown by the R1 recording current (f1), while the recording currentcorresponding to R2 record signal is not supplied.

In the case of the recording circuit 713b, the output (c2) of the signalamplitude sense circuit 783 goes to the H level when the R2 switchcontrol signal is sensed. The output (c2) of the signal amplitude sensecircuit 783 is inverted by the inverter 784 to produce a signalamplitude sense circuit inverted signal (e2'). Because of this, whilethe R2 switch control signal is being sensed, the switching signal (e2),the output of the AND gate 788, is placed at the L level. During thisperiod of time, the output off circuit 789 makes the amplifier 790inactive, preventing the switch control signal in the record RF signalfrom being supplied as a recording current.

The Q output (d2) of the flip-flop 786 reset to the L level goes to theH level when the switch control signal at the head of R2 record signalis sensed. The Q output goes to the L level when the switch controlsignal at the end of R2 record signal is sensed. Because no R1 switchcontrol signal is sensed, there is no change in the Q output. Similarly,from this time on, the Q output of the flip-flop 786 is inverted eachtime the R2 switch control signal is sensed.

The switching signal (e2) goes to the H level when all the inputs to theAND gate 788 are at the H level, or when the signal amplitude sensecircuit inverted output (e2') and the output (d2) of the flip-flop 786are all at the H level. Since the output off circuit 789, when theswitch signal (e2) is at the H level, makes the amplifier 790 active,the recording current corresponding to R1 record signal is not suppliedas shown by the R2 recording current (f2), while the recording currentcorresponding to R2 record signal is supplied.

Similarly, during an insert recording operation, partial rewriting canbe done by using the switch control signal added to before and after therecord signal to be insert recorded by the recording circuits 713a and713b to control the switching so as to record only the signalssandwiched by switch control signals.

Referring to FIG. 162, the construction of another recording circuitwill be explained. FIGS. 163 and 164 show the operation sequence ofvarious portions of the FIG. 162 recording circuit during a normalrecording operation and during an insert recording operation.

In the record RF signal (a) of this recording circuit, the first switchcontrol signal inserted before and after R1 record signal (hereinafter,referred to as the R1 switch control signal) has a larger amplitude thanthat of the second switch control signal inserted before and after R2record signal (hereinafter, referred to as the R2 switch control signal)as shown in FIGS. 163 and 164. This embodiment provides a recordingcircuit which senses either R1 switch control signal or R2 switchcontrol signal on the basis of the amplitude difference between them.For example, the recording circuit 713a senses the R1 switch controlsignal to switch between the active and inactive states, and therecording circuit 713b senses the R2 switch control signal to switchbetween the active and inactive states.

The record RF signal transferred from the rotary transformer is suppliedto input 1 and input 2 of the recording circuits 713a and 713b. Thesupplied record RF signal is divided into two signals, one of which issupplied to the emitter follower 781 and the other of which is suppliedto the signal amplitude sense circuit 783.

The signal amplitude sense circuit 783 of the recording circuit, whosefunction differs from that of the recording circuits of FIGS. 156 and159, has the upper and lower limits of comparison reference to sense theamplitude difference between the record signal, R1 switch control signaland R2 switch control signal contained in the record RF signal, producesa H-level signal when the amplitude level of the signal lies within thelimit range and a L-level signal when the level exceeds the range. Forexample, in the case of the record RF signal (a) of FIG. 163, by settingthe upper limit larger than the amplitude of R1 switch control signaland by setting the lower limit larger than the amplitude of R2 switchcontrol signal, R1 switch control signal can be sensed. Further, bysetting the upper limit larger than the amplitude of R2 switch controlsignal whose amplitude is smaller than that of R1 switch control signaland by setting the lower limit larger than the amplitude of the recordsignal, R2 switch control signal can be sensed.

The sensing level setting input is fixed to a suitable potential. Bychanging the potential, it is determined whether R1 switch controlsignal or R2 switch control signal is sensed. The recording circuit thatsenses the former operates as the recording circuit 713a and therecording circuit that senses the latter operates as the recordingcircuit 713b. This prevents the recording circuits of the sameconfiguration 180° opposite to each other from operating simultaneously,which eliminates the EX-OR gate 787 used in the previous embodiment.

Since the recording circuit 713a of FIG. 162 records only the R1 recordsignal sandwiched by R1 switch control signals and the recording circuit713b records only the R2 record signal sandwiched by R2 switch controlsignals, it is not necessary to perform control using the carrier sensecircuit in order to supply only the signal to be recorded.

The inverter 784, initial setting circuit 785, and flip-flop 786 havethe same construction as those in the recording circuit of FIG. 156, andfunction in the same manner.

The AND gate 788 differs from those in FIGS. 156 and 159 in that it hastwo inputs because the carrier sense circuit is removed. The AND gate788, when both the signals sent from the inverter 784 and flip-flop 786are at the H level, supplies a H level signal to the output off circuit789, making the amplifier 790 active.

Referring to FIGS. 163 and 164, the operation sequence of variousportions of the FIG. 162 recording circuit during a normal recordingoperation and during an insert recording operation will be explained.

The record RF signal (a) transferred from the rotary transformer issupplied to input 1 and input 2 of the recording circuits 713a and 713b.The record RF signal is divided into two signals, one of which issupplied to the emitter follower 781 and the other of which is suppliedto the signal amplitude sense circuit 783.

In the case of the recording circuit 713a, the output (c1) of the signalamplitude sense circuit 783 goes to the H level when R1 switch controlsignal is sensed. The output (c1) of the signal amplitude sense circuit783 is inverted by the inverter 784 to produce a signal amplitude sensecircuit inverted signal (e1'). Because of this, while the R1 switchcontrol signal is being sensed, the switching signal (e1), the output ofthe AND gate 788, is placed at the Lo level. During this period of time,the output off circuit 789 makes the amplifier 790 inactive, preventingthe switch control signal in the record RF signal from being supplied asa recording current.

The Q output (d1) of the flip-flop 786 previously reset to the L levelgoes to the H level when the switch control signal at the head of R1record signal is sensed. The Q output goes to the L level when theswitch control signal at the end of R1 record signal is sensed. Becauseno R2 switch control signal is sensed, there is no change in the Qoutput. Similarly, from this time on, the Q output of the flip-flop 786is inverted each time R1 switch control signal is sensed.

The switching signal (e1) goes to the H level when all the inputs to theAND gate 788 are at the H level, or when the signal amplitude sensecircuit inverted output (e1') and the output (d1) of the flip-flop 786are all at the Hi level. Since the output off circuit 789, when theswitch signal (e1) is at the H level, makes the amplifier 790 active,the recording current corresponding to R1 record signal is supplied asshown by the R1 recording current (f1), while the recording currentcorresponding to R2 record signal is not supplied.

In the case of the recording circuit 713b, the output (c2) of the signalamplitude sense circuit 783 goes to the H level when R2 switch controlsignal is sensed. The output (c2) of the signal amplitude sense circuit783 is inverted by the inverter 784 to produce a signal amplitude sensecircuit inverted signal (e2'). Because of this, while the R2 switchcontrol signal is being sensed, the switching signal (e2), the output ofthe AND gate 788, is placed at the L level. During this period of time,the output off circuit 789 makes the amplifier 790 inactive, preventingthe switch control signal in the record RF signal from being supplied asa recording current.

The Q output (d2) of the flip-flop 786 previously reset to the L levelgoes to the H level when the switch control signal at the head of R2record signal is sensed. The Q output goes to the L level when theswitch control signal at the end of the R2 record signal is sensed.Because no R1 switch control signal is sensed, there is no change in theQ output. Similarly, from this time on, the Q output of the flip-flop786 is inverted each time R2 switch control signal is sensed.

The switching signal (e2) goes to the H level when all the inputs to theAND gate 788 are at the H level, or when the signal amplitude sensecircuit inverted output (e2') and the output (d2) of the flip-flop 786are all at the H level. Since the output off circuit 789, when theswitch signal (e2) is at the H level, makes the amplifier 790 active,the recording current corresponding to R1 record signal is not suppliedas shown by the R2 recording current (f2), while the recording currentcorresponding to R2 record signal is supplied.

Similarly, during an insert recording operation, partial rewriting canbe done by using the switch control signal added to before and after therecord signal to by insert recorded by the recording circuits 713a and713b to control the switching so as to record only the signalssandwiched by switch control signals.

Next explained will be a concrete construction of the signal amplitudesense circuit 783 of the FIG. 162 recording circuit, referring to theschematic diagram of FIG. 165 and the operation sequence of FIG. 166.

After the record RF signal (a) is supplied to the signal amplitude sensecircuit 783, the amplitude level of the record RF signal is sensed aspassing through the rectifier circuit 792 and low-pass filter 793, andthe amplitude level sense signal (x) is sent to two comparators 794 and795.

The comparator 794 produces a H-level signal when the input signal islower than threshold voltage V1, and produce a L level signal when theinput signal is higher than V1. The comparator 795 produces a L-levelsignal when the input signal is lower than threshold voltage V2, andproduce a H-level signal when the input signal is higher than V2.

The AND gate 796, when both outputs of the comparators 794 and 795 areat the H level, produces a H-level signal, which is R1 switch controlsignal or R2 switch control signal.

The threshold voltages VT1 and VT2 of the comparators 794 and 795 aredivided by three resistors Z1, Z2, and Z3 to set a specified potential.By controlling the threshold voltages VT1 and VT2 by the potentialsupplied to the sensing level setting input, it is possible to selectand sense either R1 switch control signal or R2 switch control signal.

As shown by the amplitude level sense signal (x) of FIG. 166, to senseR1 switch control signal, threshold voltage VT1 is set at V1 larger thanthe amplitude of R1 switch control signal and threshold voltage VT2 isset at V2 larger than the amplitude of the record signal whose amplitudeis smaller than that of R1 switch control signal. At this time, therecording circuit operates as the recording circuit 713a.

To sense R2 switch control signal, threshold voltage VT1 is set at V1'smaller than the amplitude of R1 switch control signal and larger thanthe amplitude of R2 switch control signal, and threshold voltage VT2 isset at V2' smaller than the amplitude of R2 switch control signal andlarger than the amplitude of the record signal. At this time, therecording circuit operates as the recording circuit 713b.

In the case of the recording circuit 713a, since threshold voltage VT1is set at V1, the comparator output (y1) is always at the H level.Because threshold voltage VT2 is set at V2, the comparator output (z1)is at the H level only during the time when R1 switch control signal isbeing supplied.

The signal amplitude sense circuit output (e1) of AND gate 796 goes tothe H level when both of the comparator output (y1) and comparatoroutput (z1) are at the H level.

In the case of the recording circuit 713b, since threshold voltage VT1is set at VT1', the comparator output (y2) is at the L level only duringthe time when R1 switch control signal is being supplied. Becausethreshold voltage VT2 is set at V2', the comparator output (z2) is atthe H level only during the time when R1 switch control signal and R2switch control signal are being supplied.

Since the signal amplitude sense circuit output (e2) of AND gate 796goes to the H level when both of the comparator output (y2) andcomparator output (z2) are at the H level, it is at the L levelaccording to the comparator output (y2) during the time when R1 switchcontrol signal is being supplied, and is at the H level during the timewhen R2 switch control signal is being supplied.

The signal amplitude circuit, to which the RF detector shown in FIG. 145is applied, uses two comparators 794 and 795 to sense only signals whoseamplitude is within a certain range. This signal amplitude circuit hasthe same effect as explained in the embodiments of the RF detector.

In the recording circuits in the embodiments shown in FIGS. 156, 159,and 162, a switch control signal whose amplitude is sufficiently largerthan that of the record signal. However, adding a switch control signalwhose amplitude is smaller than that of the record signal enablessimilar control, since what is required is the ability to sense theamplitude difference between the record signal and the switch controlsignal.

Other types of logic circuits may be used instead of the logic circuitsused in those embodiments including inverters, AND gates, EX-OR gates,and flip-flops, as long as those new logic circuits allow basically thesame control.

While the recording circuits in FIGS. 156 and 159 incorporate an initialsetting circuit, the recording circuit may be provided with inputterminals for initial setting and the initial setting be done via sliprings. In this case, since what is required is to have a plurality ofrecording circuits undergo initial setting simultaneously, it issufficient to increase the slip rings by one channel. Because therecording circuits in those embodiments are available in IC chips, it iseasy to install them within the rotary drum.

The above recording circuit may be applied to a magnetic recording andreproduction apparatus described hereinafter.

The recording and reproduction apparatus comprises a rotary drum havinga circumferential surface, a plurality of recording magnetic heads andreproduction magnetic heads mounted on the rotary drum which record andreproduction information signals, making contact with a magnetic taperunning so as to wrap around the circumferential surface of the rotarydrum, a plurality of recording circuits mounted in the rotary drum andconnected to the recording heads, respectively, a first control circuitprovided in each of the recording circuits, for sensing anamplitude-modulated signal which is added to at least one of front andend parts of an information signal to be recorded which is transferredto one of the recording circuits from outside the rotary drum to obtaininformation indicating an effective recording area angle with respect toa rotational direction of the rotary drum, the amplitude-modulatedsignal being modulated into different amplitude from that of theinformation signal and being transferred to one of the recordingcircuits, a second control circuit provided in each of the plurality ofrecording circuits which senses an information signal to be recordedwhich is transferred to the recording circuit from outside the rotarydrum, a third control circuit provided in each of the plurality ofrecording circuits, which brings the output stage of the recordingcircuit into an active state during the time when the first controlcircuit senses that the recording head corresponding to the recordingcircuit including the first control circuit is within the effectiverecord area angle and the second control circuit senses the informationsignal, and at least one rotary transformer connected directly to therecording circuit.

At least one of the first and second control circuit comprises thefull-wave rectifying RF detector 720 as shown in FIGS. 145 and 147. Thatis, the full-wave rectifying RF detector 720 contains at least one stageof a full-wave rectifier circuit 728 (or full-wave rectifier circuits728a and 728b) for full-wave rectifying said information signal, alow-pass filter 729 for removing the high-frequency components from theoutput signal of the full-wave rectifier circuit, and a binarizingcircuit, i.e., comparator 724 for converting the output signal of thelow-pass filter into a binary signal.

As shown in FIG. 133, the third control circuit 730 includes a pluralityof photodetectors 271a and 271b installed respectively at the positionscorresponding to the magnetic heads P1 and P2 on the rotary drum, andthe recording and reproduction apparatus includes an array 272 of aplurality of light emitting elements densely arranged in an arcuatedpattern on the stationary drum, each of the light emitting diodes beingwithin a range corresponding to a reproducible area, and correspondingin position to the photodetectors, and wherein the reproduction circuitare connected directly to the photodetectors to receive a control signalgenerated from each of the photodetectors of the third control circuitduring when the photodetectors detect light from the light emittingelements.

Next explained will be an embodiment according to a manufacturing methodof a rotary transformer apparatus used in the present invention,referring to FIGS. 169A through 169C.

One known rotary transformer is a coaxial rotary transformer, in whichthe magnetic cores are magnetically separated for each channel in orderto reduce channel variations and crosstalk, which raise problemsespecially in wideband, high transfer rate VTRs such as HDTV VTRs. Thecoaxial rotary transformer is constructed in such a manner that arotating element and a stationary element are coaxially arranged andcomposed of multiple channels of magnetic cores magnetically separatedfor each channel and winding coils provided for each channel of magneticcores. Of the magnetic cores of the rotating element and the stationaryelement, those whose inner circumference side is wound with windingcoils have first cores with a winding slot and second cores without awinding slot placed alternately along the axis.

The present invention is characterized by comprising the steps of, inmanufacturing a coaxial rotary transformer apparatus described above,preparing as the first cores first core materials with a ring-likesquare groove serving as the winding slot in the face perpendicular tothe axis, and as the second cores second core materials of a flat ringshape, inserting the winding coils in the ring-like square groove(circular channel-shaped groove), then alternately laminating thosefirst and second core materials together with short rings if used, andgrinding the inner circumference surface of the first and second corematerials laminated until the winding coils are exposed.

The embodiments shown in FIGS. 144 to 166 are applied to a recordingcircuit, but this may be applied to an erasing circuit.

FIG. 167 is a sectional view showing magnetic cores whose innercircumference side is provided with winding coils among the magneticcores of the rotating element and the stationary element in the presentembodiment, before the grinding is done. FIG. 168 is a sectional view ofthe rotary transformer after the grinding.

In FIGS. 167 and 168, numeral 800 indicates a hollow magnetic core madeof soft magnetic material such as ferrite, which is constructed in sucha manner that first cores 801 with a winding slot 802 and second cores803 without a winding slot are laid one on top of another alternatelyvia short rings along the axis. The reason why the first cores 801 areseparated from the second cores 803 in the magnetic core 800 is tofacilitate the placement of winding coils from the inside, which isgenerally difficult. The short rings 804 are used to magneticallyseparate magnetic cores for each channel. In the winding slots 802,winding coils such as enameled wire are placed. The entire magnetic core800 is housed in a cylindrical housing 806 made of nonmagnetic metalsuch as aluminum.

In practice, the winding coils are provided with lead wires, which arepassed through lead wire grooves or the like in the magnetic core 800and housing 806 and drawn outside, although not shown in the figure.

FIGS. 169A through 169C are perspective views of a core in connectionwith the manufacturing processes of rotary transformers according to thepresent embodiment. As shown in FIGS. 167 and 169A, for the first cores801, first core materials are prepared which have a ring-like squaregroove 807 serving as a winding slot 802 formed in the faceperpendicular to the axis by forming a thicker portion 808 along theinnermost circumference. Then, as shown in FIGS. 167 and 169B, a windingcoil 805 is inserted in the ring-like square groove 807. In this case,the winding coil 805 is limited by the thicker portion 808, this assuresthat the winding coil is located in place, preventing any portion toprotrude toward the inside and fall off the core 801.

On the other hand, for the second cores 803, second core materials of aflat ring shape are prepared whose inside diameter is almost the same asthat of the first core material serving as the first core shown in FIGS.169A and 169B. Short rings whose inside diameter is almost the same asthat of the second core material are also prepared. The first corematerials with the winding coils 805 inserted in the ring-like squaregrooves 807, the second core materials, and the short rings are laid oneon top of another as shown in FIG. 167. Then, the resulting assembly isall housed in the cylindrical housing 806. In this state, the opening ofthe ring-like groove 807 of the first core is closed with the secondcore material, which forms a ring-like closed space between the firstcore material and the second core material, allowing the winding coil805 to rest in place stably in the ring-like closed space.

Then, the inner circumference surface of the first and second corematerials and short rings are ground with a lathe or the like until thebroken lines in FIG. 167 are reached. After the grinding of the innercircumference surface of the first and second core materials and shortrings is completed, as for the shape of the first core material, thethicker portion 808 in FIGS. 169A and 169B are removed as shown in FIG.169C to make the inner circumference of the closed space open,permitting the winding coil 805 to be exposed. As a result, the entireshape of the magnetic core 800 is as shown in FIG. 168, and a coaxialrotary transformer apparatus can be obtained.

With the manufacturing method of a rotary transformer apparatusaccording to the present invention, the placement of winding coils iseasier, and an improvement in the yield and a reduction in themanufacturing cost are possible.

Although in the above embodiment, a 4-channel rotary transformerapparatus is used, the number of channels is not restricted to 4. Whilein the embodiment, two circuits of winding coils are placed in a singlewinding slot, the present invention may be applied to a rotarytransformer apparatus with more circuits of winding coils in a windingslot.

Next, an embodiment of a mounting method of a scanner section in thepresent invention will be explained, refer ring to FIGS. 170A through170D, and FIGS. 171 and 172. FIGS. 170A through 170D are views used forexplaining the construction of a reproduction circuit board unit in thescanner section and its manufacturing processes. As shown in FIG. 170A,a reproduction circuit IC 902, and passive element chip parts includinga resistor 903 and a capacitor 904 are mounted automatically on areproduction circuit board 901. In parallel with this, as shown in FIG.170B, a photodetector bare chip 906 is mounted on a photodetector board905 and wired onto the board 905 with bonding wires 907. After operationcheck, the resulting assembly is sealed with a transparent resin asshown in FIG. 170C. Then, by securing the photodetector board 905 ofFIG. 170C on the reproduction circuit board 901 of FIG. 170A with anadhesive 909, a reproduction circuit board unit where the reproductioncircuit and the photodetector are integrated into a hybrid IC can beobtained.

The sealing of the photodetector bare chip 906 with the transparentresin 908 may be done after the photodetector board 905 has been securedonto the reproduction circuit board 901.

FIG. 171 is another embodiment of the reproduction circuit board unit,which has the photodetector bare chip 906 mounted directly on thereproduction circuit board 901 without using a photodetector board asshown in FIGS. 170A through 170D.

In FIG. 172, a reproduction circuit board 1001 is mounted on the bottomof the rotary drum 1003, and a recording circuit board 2001 is mountedon its top, with an IC chip containing recording circuits 713a and 713bmounted on the bottom face of the recording circuit board 2001, and anIC chip containing reproduction circuits 714a and 714b mounted on thebottom face of the reproduction circuit board 1001. Recordphotodetectors 1005a and 1005b are mounted on the top face of therecording circuit board 2001, and reproduction photodetectors 1006a and1006b are mounted on the bottom face of the reproduction circuit board1001. The photodetectors 1005a, 1005b, 1006a, and 1006b arephotodetector bare chips sealed with a transparent resin.

An upper stationary drum 1004a and a lower stationary drum 1004b areplaced above and under the rotary drum, respectively. A recording LEDarray 1007 and a reproduction LED array 1008 are placed on LED boards2010 and 1010 provided on the stationary drums 1004a and 1004b, so as toface the recording photodetectors 1005a and 1005b and the reproductionphotodetectors 1006a and 1006b. Grooves or through holes are formed inthe LED boards 2010 and 1010 as formed in the board 400 shown in FIG.135. Within those grooves or through holes, the LED arrays 1007 and 1008are provided.

Conventionally, as shown in broken lines in FIG. 172, the reproductionphotodetectors (1006a, 1006b) are mounted together with the recordingphotodetectors (1005a, 1005b) on the recording circuit board 2001. Inaddition, the reproduction LED array (1008) is mounted on the upperstationary drum 1004a so as to face the reproduction photodetectors(1006a, 1006b). As a result, to connect the reproduction photodetectorson the recording circuit board 2001 to the reproduction circuit board1001, as many lead wires for transmitting the control signal from thephotodetectors as the reproduction heads are required, which is one ofcauses of increasing the labor and time required to manufacture scannersand the production cost as the number of heads increases.

However, by placing the reproduction photodetectors on the reproductioncircuit board 1001 as shown in FIG. 172, and consequently shifting thereproduction LED array to the lower stationary drum 1004b, the drawingof lead wires for connecting the reproduction photodetectors to thereproduction circuit board 1001 becomes unnecessary, which is veryhelpful in the manufacture.

While in the above embodiments, rotary transformer-type VTRs have beenexplained, this invention may be applied to VTRs employing othermagnetic head-mounted systems such as the disk type or the middle drumtype.

Although in the above embodiments, the switching is done between the1-channel rotary transformer and the 2-channel recording circuit orreproduction circuit, the invention may be applied to a recordingcircuit or reproduction circuit with more channel or a combinationrecording and reproduction circuit with more channels. For instance, ifthere are eight channels of recording heads and recording circuits andeight channels of reproduction heads and reproduction circuits, and theeffective recording area angle is 180°, the rotary transformer may haveeight channels.

While in the above embodiments, a LED array-based system is used as acontrol system of drum-mounted circuits, the recording circuits,reproduction circuits, and erase circuits on the rotary drum may becontrolled by different control systems, such as three different typesof control systems for drum-mounted circuits disclosed in PublishedUnexamined Japanese Patent Application No. 1-127911. For instance, therecording circuits and erase circuits may use the LED array-basedcontrol system, and the reproduction circuits use thephotoreflector-based system.

Further, the erase circuits may employ the active/inactive controlsystem as do the recording circuits. Since in insert editing, the erasecircuits operates whenever the recording circuits operate, if the tapeformat permits, for example, the recording LED array may be used as theerase LED array for the erase circuit control. In this case, there is nopossibility that the erase circuits become active, since theaforementioned RF detector does not operated unless the erase RF signalis transferred to the erase circuits within the rotary drum.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, representative devices, andillustrated examples shown and described herein. Accordingly, variousmodifications may be without departing from the spirit or scope of thegeneral inventive concept as defined by the appended claims and theirequivalents.

What is claimed is:
 1. A magnetic recording/reproduction apparatuscomprising:a rotary drum having a circumferential surface; tape runningmeans for rotating said rotary drum to run a magnetic tape with themagnetic tape being in contact with, at least, part of thecircumferential surface of said rotary drum; a plurality of magneticheads installed on said rotary drum so that said magnetic heads arerotated together with said rotary drum, with said magnetic heads beingin contact with the magnetic tape; a plurality of amplifying circuitmeans respectively connected to said magnetic heads and installed onsaid rotary drum so that they rotate together with said rotary drum,said amplifying circuit means being selectively active and inactive; atleast one rotary transformer having a core in which a slot having acircular shape is formed, a winding formed of at least one metal platecoil received in said slot and having both coil ends, said metal platecoil having a shape corresponding to the circular shape of said slot,and lead-in metal plate wires formed integral with said metal plate coilby-etching or die-cutting so that they extend from the both coil ends ofsaid metal plate coil, said lead-in-metal plate wires having terminalends connected to said amplifying circuit means; and control means formaking said magnetic heads perform at least one of data-recording anddata-reproduction through said amplifying circuit means, and said rotarytransformer.
 2. A magnetic recording/reproduction apparatus according toclaim 1, wherein said rotary transformer has leading holes for leadingelectric lead-in wires, and said lead-in wires are folded along saidleading holes.
 3. A magnetic recording/reproduction apparatus accordingto claim 2, wherein said lead wires are covered with insulating sheathrespectively.
 4. A magnetic recording and reproduction apparatuscomprising:a rotary drum having a circumferential surface; a stationarydrum disposed opposite to said rotary drum; tape running means forrotating said rotary drum to run a magnetic tape with the magnetic tapebeing in contact with at least part of the circumferential surface ofsaid rotary drum; magnetic head means having at least first and seconderasing magnetic heads used for erasing a record signal and a pluralityof recording magnetic heads used for recording an information signal,said first and second erasing magnetic heads and said recording magneticheads being installed on said rotary drum so that they rotate togethertherewith, and are in contact with the magnetic tape; at least first andsecond erasing circuit means installed on said rotary drum so that theyrotate together therewith, and connected directly to said first andsecond erasing magnetic heads, respectively, to output at least firstand second erasing signals to said first and second erasing magneticheads, respectively; detection means for detecting the rotationalpositions of said rotary drum which correspond to an area of the rangeof said magnetic tape to be erased; erasing control means installed onsaid rotary drum, for selectively activating said first and seconderasing circuit means in accordance with a detection signal from saiddetection means; a plurality of recording circuit means connecteddirectly to said recording magnetic heads, respectively, and installedon said rotary drum so that they rotate together therewith, saidrecording circuit means being selectively active and inactive; and arotary transformer which has at least one core with a slot, and at leastfirst and second coils inserted in said slot of said core, and connecteddirectly to said first and second erasing circuit means, respectively,said first and second coils being wound around an axis of rotation ofsaid rotary drum.
 5. A magnetic recording and reproduction apparatuscomprising:rotary drum having a circumferential surface; a stationarydrum disposed opposite to said rotary drum; tape running means forrotating said rotary drum and running a magnetic tape with said tapebeing in contact with at least part of the circumferential surface ofsaid rotary drum; magnetic head means having a plurality of erasingmagnetic heads used for erasing a record signal, and a plurality ofrecording magnetic heads used for recording information signals in saidmagnetic tape, said erasing magnetic heads and said recording magneticheads being installed on said rotary drum so that they rotate togethertherewith and are in contact with said magnetic tape; a plurality oferasing circuit means installed on said rotary drum so that said erasingcircuit means rotate together therewith, and connected directly to saiderasing magnetic heads, respectively, to output an erasing signal toeach of said erasing heads; a plurality of recording circuit meansconnected directly to said recording magnetic heads, respectively, tooutput an information signal to each of said magnetic heads, andinstalled on said rotary drum; at least one rotary transformer connectedto said recording circuit means and said erasing circuit means, saidrotary transformer having at least one core with a slot, and at leastfirst and second coils inserted in said slot, and said first coil beingconnected directly to at least one of said erasing circuit means, andsaid second coil being connected directly to at least one of saidrecording circuit means, said first and second coils being wound aroundan axis of rotation of said rotary drum; and detection means fordetecting those rotational positions of said rotary drum whichcorrespond to an area of the range of said magnetic tape to be erased orrecorded; and erasing and recording control means installed on saidrotary drum, for selectively activating said erasing circuit means andsaid recording circuit means which are connected to said first andsecond coils, respectively, in accordance with an output from saiddetection means.
 6. A magnetic recording and reproduction apparatuscomprising;a rotary drum having a circumferential surface; a stationarydrum disposed opposite to said rotary drum; tape running means forrotating said rotary drum and running a magnetic tape with the magnetictape being in contact with at least part of the circumferential surfaceof said rotary drum; magnetic head means having a plurality of erasingmagnetic heads used for erasing a record signal, a plurality ofrecording magnetic heads used for recording an information signal, and aplurality of reproduction magnetic heads used for reproducing the recordsignal from said magnetic tape, said erasing, recording and reproductionmagnetic heads being installed on said rotary drum so that they rotatetogether therewith and are in contact with said magnetic tape; aplurality of erasing circuit means installed on said rotary drum so thatsaid erasing circuit means rotate together therewith, and connecteddirectly to said erasing magnetic heads, respectively, to output anerasing signal to each of said erasing heads; a plurality of recordingcircuit means connected directly to said recording magnetic heads,respectively, and installed on said rotary drum so that they rotatetogether therewith; a plurality of reproduction circuit means connecteddirectly to said reproduction magnetic heads, respectively, andinstalled on said rotary drum so that they rotate together therewith; atleast one rotary transformer connected to said reproduction circuitmeans and said erasing circuit means, said rotary transformer having atleast one core with a slot, and at least first and second coils insertedin said slot, and said first coil beinq connected directly to at leastone of said reproduction circuit means and said second coil beingconnected directly to at least one of said erasing circuit means, saidfirst and second coils being wound around an axis of rotation of saidrotary drum; detection means for detecting the rotational positions ofsaid rotary drum which correspond to an area of the range of saidmagnetic tape to be erased or reproduced; and erasing and reproductioncontrol means installed on said rotary drum, for selectively activatingsaid erasing circuit means and said reproduction circuit means which areconnected to said first and second coils, respectively, in accordancewith an output from said detection means.
 7. A magnetic recording andreproduction apparatus comprising:a scanner including a rotary drumhaving a circumferential surface, and a stationary drum opposing saidrotary drum; mechanical driving means for driving said rotary drum torotate and causing a magnetic tape to travel in contact with at least apart of the circumferential surface of said rotary drum; magnetic headmeans having a plurality of recording magnetic heads used for recordingan information signal on the magnetic tape, and a plurality of erasingmagnetic heads used for erasing a record signal, said recording anderasing magnetic heads being mounted on said rotary drum so as to bebrought into contact with said magnetic tape and rotate togethertherewith; a plurality of recording circuits mounted within said rotarydrum so as to rotate together therewith, said recording circuits eachhaving input and output terminal means, said output terminal means ofeach of said recording circuits being coupled directly to acorresponding one of said plurality of magnetic heads, and saidrecording circuits being controlled between active and inactive states;a plurality of erasing circuits mounted within said rotary drum so as torotate together therewith, said erasing circuits each having input andoutput terminal means, said output terminal means of each of saiderasing circuits being coupled directly to a corresponding one of saidplurality of magnetic heads, and said erasing circuits being controlledbetween active and inactive states; a rotary transformer unit having arotary member mounted on said rotary drum and a stationary member, saidrotary and stationary members having primary and secondary coil means,at least one of said primary and secondary coil means being constitutedby a plurality of coils inserted in a slot, and said coils of each ofsaid secondary coil means being coupled directly to said input terminalmeans of said recording circuits, respectively, said coils being woundaround an axis of rotation of said rotary drum; another rotarytransformer unit having a rotary member mounted on said rotary drum anda stationary member, said rotary and stationary members having primaryand secondary coil means, at least one of said primary and secondarycoil means being constituted by a plurality of coils inserted in a slot,and said coils of each of said secondary coil means being coupleddirectly to said input terminal means of said erasing circuits,respectively; first control means mounted on said stationary drum, saidfirst control means containing an arcuated-pattern light-emittingelement array constructed by a plurality of light-emitting elementsarranged in an arcuated shape in the direction of rotation of saidrotary drum, and a plurality of photodetectors placed in the positionsof said rotary drum which correspond to at least one of said recordingand erasing heads, respectively, for outputting a signal indicating theperiod of time during which at least one of said recording and erasingheads is within a range of said light-emitting element array; one secondcontrol means provided in each of said plurality of recording circuitsfor sensing an information signal to be recorded which is transferred tosaid recording circuit from outside said rotary drum; another secondcontrol means provided in each of said plurality of erasing circuits forsensing an erasing signal to be erased which is transferred to saiderasing circuit from outside said rotary drum; one third control meansprovided in each of said plurality of recording circuits which brings atleast the output stage of the recording circuit into an active stateduring the time when said first control means senses that one ofrecording magnetic heads is within the range of said light-emittingelement array and said one second control means senses an informationsignal; and another third control means provided in each of saidplurality of erasing circuits which brings at least the output stage ofthe erasing circuit into an active state during the time when said firstcontrol means senses that one of said erasing heads is within the rangeof said light-emitting element array and said another second controlmeans senses an erasing signal.
 8. A magnetic recording and reproductionapparatus comprising:a rotary drum having a circumferential surface; aplurality of recording magnetic heads and reproduction magnetic headsmounted on said rotary drum which record and reproduction informationsignals, making contact with a magnetic tape running so as to wraparound the circumferential surface of the rotary drum; a plurality ofrecording circuits mounted in said rotary drum and connected to saidrecording heads, respectively; first control means provided in each ofsaid recording circuits, for sensing an amplitude-modulated signal whichis added to at least one of front and end parts of an information signalto be recorded which is transferred to one of said recording circuitsfrom outside said rotary drum to obtain information indicating aneffective recording area angle with respect to a rotational direction ofsaid rotary drum, the amplitude-modulated signal being modulated intodifferent amplitude from that of the information signal and istransferred to one of said recording circuits; second control meansprovided in each of said plurality of recording circuits which senses aninformation signal to be recorded which is transferred to the recordingcircuit from outside said rotary drum; third control means provided ineach of said plurality of recording circuits, which brings the outputstage of the recording circuit into an active state during the time whensaid first control means senses that the recording head corresponding tothe recording circuit including said first control means is within theeffective record area angle and said second control means senses saidinformation signal; and at least one rotary transformer connecteddirectly to said recording circuit means.
 9. A magnetic recording andreproduction apparatus according to claim 6, wherein said detectionmeans includes a plurality of photodetectors for erasing andreproduction which are mounted on said rotary drum at positionscorresponding to said erasing and reproduction magnetic heads,respectively, and wherein said apparatus includes a plurality of erasinglight emitting diodes which are densely arranged in an arcuated pattern,each of said erasing light emitting diodes being within a rangecorresponding to an erasing area, said erasing light emitting diodescorresponding in position to said photodetectors for erasing, and aplurality of reproduction light emitting diodes which are denselyarranged in an arcuated pattern, each of said reproduction lightemitting diodes being within a range corresponding to an effectivereproduction area, said reproduction light emitting diodes correspondingin position to said photodetector for reproduction, and wherein saiderasing circuit means is controlled by a control signal generated fromsaid photodetector of said detection means when said photodetectordetects light of the erasing light emitting diodes, and saidreproduction circuit means is controlled by a control signal generatedfrom said photodetector of said detection means when said photodetectorsdetect light of the reproduction light emitting diodes.
 10. A magneticrecording and reproduction apparatus according to claim 5, wherein saiddetection means includes a plurality of photodetectors for recording anderasing which are mounted on said rotary drum at positions correspondingto said erasing and recording magnetic heads, respectively, and whereinsaid apparatus includes a plurality of recording light emitting diodeswhich are densely arranged in an arcuated pattern and mounted on saidstationary drum, each of said recording light emitting diodes beingwithin a range corresponding to an effective recording area, saidrecording light emitting diodes corresponding in position to saidphotodetectors for recording, and a plurality of erasing light emittingdiodes which are densely arranged in an arcuated pattern, each of saiderasing light emitting diodes being within a range corresponding to anerasing area, said erasing light emitting diodes corresponding inposition to said photodetectors for erasing, and wherein said recordingcircuit means is controlled by a control signal generated from saidphotodetector of said detection means when said photodetector detectslight of the recording light emitting diodes, and said erasing circuitmeans is controlled by a control signal generated from saidphotodetector of said detection means when said photodetector detectslight of the erasing light emitting diodes.
 11. A magnetic recording andreproduction apparatus according to claim 4, wherein said erasingcontrol means includes a plurality of photodetectors installedrespectively at the positions corresponding to said magnetic heads onsaid rotary drum, and said apparatus includes a plurality of lightemitting elements densely arranged in an arcuated pattern on saidstationary drum, each of said light emitting diodes being within a rangecorresponding to an erasing area in correspondence with saidphotodetectors, and wherein said first and second erasing circuit meansare connected directly to said photodetectors of said erasing controlmeans, for supplying the erasing signal to each of said first and seconderasing magnetic heads in response to a control signal generated fromeach of said photodetectors of said erasing control means during whensaid photodetectors detect light from said light emitting elements. 12.A magnetic recording and reproduction apparatus according to any one ofclaims 7, 10, or 11, wherein said photodetectors are mounted togethersaid circuits in the same hybrid integrated circuit.
 13. An apparatusaccording to any one of claims 4-8, which includes means for windingsaid magnetic tape on the circumferential surface of said rotary drum sothat an effective wrap angle which is smaller than a total wrap anglebecomes not more than 180°, said effective wrap angle being an anglewhich covers an effective area of the magnetic tape on which aninformation signal can be recorded or reproduced and said total wrapangle being an angle at which the magnetic tape is wound around saidrotary drum; andeach of said recording circuits is activated in theeffective wrap angle, for amplifying an information signal to berecorded, and each of said reproduction circuits is activated in theeffective wrap angle, for amplifying an information signal to bereproduced.
 14. An apparatus according to claim 13, wherein when twomagnetic heads to be sequentially activated are mounted on said rotarydrum, said total wrap angle is set at more than 180°.
 15. An apparatusaccording to claim 13, wherein when three magnetic heads to besequentially activated are mounted on said rotary drum, said total wrapangle is set at more than 120°.
 16. An apparatus according to claim 13,wherein when four magnetic heads to be sequentially activated aremounted on said rotary drum, said total wrap angle is set at more than90°.
 17. A magnetic recording and reproduction apparatus according toany one of claims 4-8, wherein said rotary drum has a rotary transformerof more than 8 channels.
 18. A magnetic recording and reproductionapparatus according to any one of claims 7, 9, 10 or 11, wherein saidarcuated pattern light-emitting element array has light-emittingelements series-connected at intervals of a specified number of elementsin the arrangement direction, each series circuit being connected to apower supply.
 19. A magnetic recording and reproduction apparatusaccording to any one of claims 4-8, wherein each of said erasing circuitmeans and said recording circuit means includes an amplifier having twoinput terminals connected to two terminals of one of said coils of saidrotary transformer, respectively, and a resistor connected between saidtwo input terminals.
 20. A magnetic recording and reproduction apparatusaccording to claim 19, wherein said resistor has a resistance of 50 Ω to1,000 Ω.
 21. An apparatus according to any one of claims 4-8, whereinsaid rotary transformer has at least first and second leading holes eachformed at a position at which a wiring length between one of said firstand second circuits and one of said first and second leading holes isshortest, and each of said first and second circuits is connected to oneof said first and second coils of said rotary transformer through saidfirst and second leading holes by first and second lead-in wires,respectively.
 22. A magnetic recording/reproduction apparatus accordingto claim 5, wherein said erasing heads and said recording heads areinstalled on said rotary drum at different heights.
 23. A magneticrecording and reproduction apparatus according to claim 5, whichincludes means for controlling a timing at which at least one of saidrecording circuit means is active to be different from a timing at whichat least one of said erasing circuit means is active.
 24. A magneticrecording/reproduction apparatus according to claim 6, wherein saiderasing heads and said reproduction heads are installed on said rotarydrum at different heights.
 25. A magnetic recording and reproductionapparatus according to claim 6, which includes means for controlling atiming at which at least one of said reproduction circuit means isactive to be different from a timing at which at least one of saiderasing circuit means is active.
 26. An apparatus according to claim 6,wherein when one of said reproduction circuits is active, the remainingones thereof have a higher output impedance than said one reproductioncircuit.
 27. A magnetic recording and reproduction apparatus accordingto claim 7 or 8, wherein at least one of said first and second controlmeans contains at least one stage of a full-wave rectifier circuit forfull-wave rectifying said information signal, a low-pass filter forremoving the high-frequency components from the output signal of thefull-wave rectifier circuit, and binarizing means for converting theoutput signal of the low-pass filter into a binary signal.
 28. Amagnetic recording and reproduction apparatus according to claim 7 or 8,wherein at least one of said first and second control means contains atleast one stage of a full-wave rectifier circuit for full-waverectifying one of said information signal and said amplitude-modulatedsignal, binarizing means for converting the output signal of thefull-wave rectifier circuit into a binary signal, delay means fordelaying the binary signal supplied from the binarizing means, and an ORcircuit for ORing the signal delayed by the delay means and the binarysignal from said binarizing means.
 29. A magnetic recording andreproduction apparatus according to claim 7 or 8, wherein said rotarytransformer comprises:a stator; a rotor; an upper transformer sectionfor transferring the record signal; and a lower transformer section fortransferring the erase signal, a single winding being set in a slotformed in an upper portion of said stator in said upper transformersection, and a plurality of windings being set in a slot formed in anupper portion of said rotor, a single winding being set in a slot formedin a lower portion of said stator in said lower transformer section, anda single winding being set in a slot formed in a lower portion saidrotor.
 30. A magnetic recording and reproduction apparatus according toclaim 7, wherein said rotary member of at least one of said rotarytransformer unit and said another rotary transformer unit has a rotor,and said stationary member has an outer stator and an inner stator whichare placed coaxially with said rotor, one of said rotor and said statorshaving inner slots each having a predetermined depth larger than that ofouter slots.
 31. A magnetic recording and reproduction apparatusaccording to claim 7, wherein said rotary member of at least one of saidrotary transformer unit and said another rotary transformer unit has arotor, and said stationary member has an outer stator and an innerstator which are placed coaxially with said rotor, wherein core facingwidths between the inside of said rotor and said inner stator are largerthan core facing widths between the outside of said rotor and said outerstator.
 32. A magnetic recording and reproduction apparatus according toclaim 7, wherein said rotary member and said stationary member of atleast one of said rotary transformer unit and said another rotarytransformer unit comprise multiple channels of magnetic cores separatedfor each channel and windings provided for each channel, said magneticcores being provided with winding coils on their inner circumferenceside and including first cores with a winding slot and second coreswithout a winding slot, each of said first cores being laid on acorresponding one of said second cores, and wherein said first cores aremade of first core materials with a ring-like square groove serving assaid winding slot in a face perpendicular to the axis of said rotarymember and said stationary member, and said second cores are made ofsecond core materials of a flat ring shape, said windings being insertedin the ring-like square grooves and said first and second cores beingformed by grinding the inner circumference surfaces of said first andsecond core materials which are superimposed one another until saidwindings are exposed.
 33. A magnetic recording and reproductionapparatus according to claim 8, wherein said rotary transformer includesat least one core with a slot, and a plurality of coils inserted in saidslot, and connected directly to said recording circuits, respectively,said coils being wound around an axis of rotation of said rotary drum.34. A magnetic recording and reproduction apparatus according to claim8, wherein said rotary transformer has a rotor, and an outer stator andan inner stator which are placed coaxially with said rotor, one of saidrotor and said stators having inner slots each having a predetermineddepth larger than that of outer slots.
 35. A magnetic recording andreproduction apparatus according to claim 8, wherein said rotarytransformer has a rotor, and an outer stator and an inner stator whichare placed coaxially with said rotor, core facing widths between theinside of said rotor and said inner stator being larger than core facingwidths between the outside of said rotor and said outer stator.
 36. Amagnetic recording and reproduction apparatus according to claim 8,wherein said rotary transformer comprises multiple channels of magneticcores separated for each channel and windings provided for each channel,said magnetic cores being provided with winding coils on their innercircumference side and including first cores with a winding slot andsecond cores without a winding slot, each of said first cores being laidon a corresponding one of said second cores, and wherein said firstcores are made of first core materials with a ring-like square grooveserving as said winding slot in a face perpendicular to the axis of saidrotary member and said stationary member, and said second cores are madeof second core materials of a flat ring shape, said windings beinginserted in the ring-like square grooves and said first and second coresbeing formed by grinding the inner circumference surfaces of said firstand second core materials which are superimposed one another until saidwindings are exposed.